"'mul': no matching 0 parameter intrinsic function" - What?

Hello,

I am getting this error:

Code (Plain):

1. Shader error in 'Custom/Billboard': 'mul': no matching 0 parameter intrinsic function; Possible intrinsic functions are: ...

While compiling this line:

Code (Shader):

1. float4 vertInWorldSpace = mul(unity_ObjectToWorld, vertexInput.vertex);

(this is in a vertex program, vertexInput.vertex is a float4)

It doesn't look like I'm using mul() in a zero-parameter way. What is going on?

 

I tested your vertInWorldSpace It's correct and I haven't any error!
can you send whole shader?