asset can not be loaded

I enable android 2.3 on my developmnt board(armv7)
I just want to try some games on that, and find it can not run the games based on Unity.
There are two issue:
it print "Unity : image error", but I'm sure the image is good.(it's in assets\bin\Data\splash.png)
it print "The assembly mscorlib.dll was not found or could not be loaded." I'm also sure the dll files is in place.


Anyone meet the similar issues? Anyone can help me out? Thanks~~

01-03 20:06:54.960 538 538 D Unity : cpuarch.GetCpuFeatures() = 47
01-03 20:06:54.960 538 538 D Unity : cpuarch.GetTotalMemory() = 307
01-03 20:06:54.970 538 538 D Unity : gles_mode = 2 (integer)
01-03 20:06:54.970 538 538 D Unity : splash_mode = 1 (integer)
01-03 20:06:54.980 538 538 D dalvikvm: Trying to load lib /mnt/asec/com.ArtInGames.AirAttackHD-1/lib/libmono.so 0x40514b28
01-03 20:06:54.990 538 538 D dalvikvm: Added shared lib /mnt/asec/com.ArtInGames.AirAttackHD-1/lib/libmono.so 0x40514b28
01-03 20:06:55.410 538 538 D proxy : Added shared lib /assets/libs/armeabi-v7a/libmono.so 0x8411c334
01-03 20:06:55.410 538 538 D proxy : No JNI_OnLoad found in /assets/libs/armeabi-v7a/libmono.so 0x8411c334
01-03 20:06:55.410 538 538 D dalvikvm: Trying to load lib /mnt/asec/com.ArtInGames.AirAttackHD-1/lib/libunity.so 0x40514b28
01-03 20:06:55.420 538 538 D dalvikvm: Added shared lib /mnt/asec/com.ArtInGames.AirAttackHD-1/lib/libunity.so 0x40514b28
01-03 20:06:56.160 538 538 D proxy : Added shared lib /assets/libs/armeabi-v7a/libunity.so 0x84214544
01-03 20:06:56.200 538 538 D dalvikvm: GC_EXTERNAL_ALLOC freed 166K, 53% free 2581K/5379K, external 716K/1038K, paused 31ms
01-03 20:06:56.390 538 538 D dalvikvm: GC_FOR_MALLOC freed 8K, 53% free 2573K/5379K, external 2122K/2650K, paused 19ms
01-03 20:06:56.390 538 538 I dalvikvm-heap: Grow heap (frag case) to 8.506MB for 1440016-byte allocation
01-03 20:06:56.430 538 539 D dalvikvm: GC_FOR_MALLOC freed 0K, 42% free 3979K/6791K, external 2122K/2650K, paused 19ms
01-03 20:06:56.450 538 538 D Unity : image error
01-03 20:06:56.470 538 540 D dalvikvm: GC_CONCURRENT freed 1K, 42% free 3979K/6791K, external 2122K/2650K, paused 2ms+2ms
01-03 20:06:56.490 538 538 D dalvikvm: GC_FOR_MALLOC freed <1K, 42% free 3979K/6791K, external 2122K/2650K, paused 20ms
01-03 20:06:56.500 538 538 I dalvikvm-heap: Grow heap (frag case) to 12.507MB for 4194320-byte allocation
01-03 20:06:56.540 538 539 D dalvikvm: GC_FOR_MALLOC freed 0K, 27% free 8075K/10951K, external 2122K/2650K, paused 20ms
01-03 20:06:56.580 538 538 D Unity : onResume
01-03 20:06:56.590 146 152 D sensorHAL: Try to set interval to bma150_input, file is :/sys/class/input/input3//interval, delay is 20
01-03 20:06:56.590 146 152 D sensorHAL: Successfully set interval to bma150_input.
01-03 20:06:56.590 146 275 D sensorHAL: Try to set interval to bma150_input, file is :/sys/class/input/input3//interval, delay is 20
01-03 20:06:56.590 146 275 D sensorHAL: Successfully set interval to bma150_input.
01-03 20:06:56.660 538 540 D dalvikvm: GC_CONCURRENT freed 2K, 27% free 8090K/10951K, external 716K/2122K, paused 2ms+4ms
01-03 20:06:56.710 146 176 I ActivityManager: Displayed com.ArtInGames.AirAttackHD/com.unity3d.player.UnityPlayerActivity: +1s814ms (total +2s132ms)
01-03 20:06:56.720 230 230 W IInputConnectionWrapper: showStatusIcon on inactive InputConnection
01-03 20:06:56.780 538 545 D Unity : Creating OpenGL ES 2.0 context (RGB16 565 16/0)
01-03 20:06:56.780 538 545 D GC : <tid=545> GC Version : GC Ver0.8.0.3220
01-03 20:06:56.780 538 545 D GC :
01-03 20:06:56.810 538 545 D Unity : onSurfaceCreated
01-03 20:06:57.060 538 545 D Unity : onSurfaceChanged 600x1024
01-03 20:06:57.060 538 545 D Unity : view is 600x1024
01-03 20:06:57.080 538 545 D Unity : initUnity
01-03 20:06:57.080 538 545 D Unity : glGetString (GL10.GL_VERSION)='OpenGL ES 2.0'
01-03 20:06:57.080 538 545 V Unity : Mono path[0] = 'assets/bin/Data/Managed'
01-03 20:06:57.120 538 545 E mono : The assembly mscorlib.dll was not found or could not be loaded.
01-03 20:06:57.120 538 545 E mono : It should have been installed in the `assets/bin/Data/Managed/mono/2.0/mscorlib.dll' directory.
01-03 20:06:57.170 146 148 D dalvikvm: GC_CONCURRENT freed 1346K, 53% free 4221K/8839K, external 4069K/5269K, paused 6ms+13ms
01-03 20:06:57.310 146 275 I ActivityManager: Process com.ArtInGames.AirAttackHD (pid 538) has died.
01-03 20:06:57.330 112 112 D Zygote : Process 538 exited cleanly (1)
01-03 20:06:57.330 146 178 E InputDispatcher: channel '40778808 com.ArtInGames.AirAttackHD/com.unity3d.player.UnityPlayerActivity (server)' ~ Consumer closed input channel or an error occurred. events=0x8
01-03 20:06:57.330 146 178 E InputDispatcher: channel '40778808 com.ArtInGames.AirAttackHD/com.unity3d.player.UnityPlayerActivity (server)' ~ Channel is unrecoverably broken and will be disposed!
01-03 20:06:57.340 146 146 I WindowManager: WIN DEATH: Window{40778808 com.ArtInGames.AirAttackHD/com.unity3d.player.UnityPlayerActivity paused=false}
01-03 20:06:57.340 146 251 I WindowManager: WIN DEATH: Window{406efd88 SurfaceView paused=false}
01-03 20:06:57.420 146 279 D dalvikvm: GC_EXPLICIT freed 109K, 53% free 4166K/8839K, external 4069K/5269K, paused 47ms
01-03 20:06:57.420 146 279 I WindowManager: Setting rotation to 0, animFlags=1
01-03 20:06:57.440 146 275 I ActivityManager: Config changed: { scale=1.0 imsi=0/0 loc=en_US touch=3 keys=1/1/2 nav=1/1 orien=2 layout=36 uiMode=17 seq=4}
01-03 20:06:57.610 146 146 W InputManagerService: Got RemoteException sending setActive(false) notification to pid 538 uid 10032
01-03 20:06:57.690 230 230 D dalvikvm: GC_EXTERNAL_ALLOC freed 197K, 50% free 2919K/5767K, external 4387K/5226K, paused 47ms
01-03 20:06:59.800 146 176 D dalvikvm: GC_EXPLICIT freed 203K, 53% free 4164K/8839K, external 4069K/5269K, paused 49ms
01-03 20:07:05.040 419 419 D dalvikvm: GC_EXPLICIT freed 59K, 53% free 2569K/5379K, external 716K/1038K, paused 31ms
01-03 20:07:10.040 408 408 D dalvikvm: GC_EXPLICIT freed 11K, 53% free 2571K/5379K, external 716K/1038K, paused 28ms