Shadow error in custom Shader

I got this shader: http://pastebin.com/p1EpDadg
I simply tried to add shadows, but now It gets an error:

undeclared identifier ‘ComputeScreenPos’ at line 56 (on d3d11)

The line is

  		TRANSFER_VERTEX_TO_FRAGMENT(o)

I don’t know how to fix this. please help me.

Works now. Thanks to Namey5.
I added #include “UnityCG.cginc” to my includes
and
removed the tag “queue” = “transparent”