Blit cubemap rendertexture

Hello. How can I blit cubemap rendertexture to another cubemap rendertexture?
I need copy point light shadowmap, and when I try blit, my rendertexture is red at one face.
My rendertexture is RFloat and dimension is Cube.
For spotlight it works properly, just I use 2D RFloat texture.

 

Thank you. Yes it works when I create rendertexture with shadowmap format and 1024 size. But I have problem.
I use command buffer to copy baked shadowmap to light shadowmap before shadows are rendered, and copy of baked shadowmap works properly, but dynamic objects have not affect when rendering into point light shadowmap.
I try do something similar to cached shadows feature.

 

All works properly if i use 6 command buffers to copy each face before each faces rendered. Thank you.

 

I have new problem. Shadowmap resolution depends on:
1. Quality Settings or Light shadow resolution setting
2. Camera rendering resolution
So i can't use ONE baked (or prerendered) cubemap for cameras with diferrent resolution, also i can't use this in game view and scene view when resolution of shadowmaps are different.
I can't use because CopyTexture requires equal texture resolution.
Is there any other solution to blit 2 cubemaps render textures by faces?

 

If i use CopyTexture and textures with different resolutions i got error about that sizes is not equals.
Cubemap resolution is depend on camera resolution, so for different cameras i would need different copies just in different resolutions of my textures.