how to use v2f 6 pic uv ?

i want to use 6 layer uv to make a map tile,but 5,6 layer not work, how to fix this?target 3.0 still not work

 

You might be running out of vertex shader outputs. Try using a float4 instead and pack two UVs per vertex output variable, i.e.:
o.uv0uv1 = float4(TRANSFORM_TEX(_Tex0, i.uv), TRANSFORM_TEX(_Tex1, i.uv));

Alternatively, just do the TRANSFORM_TEX() in the fragment shader, they're extremely cheap, and it may actually be faster than transferring all that data from the vertex shader to the fragment (if you're not using this for mobile).