When using the following AGAL code my particle is rendered:

Vertex Shader:
"m44 op, va0, vc0 \n" +
"mov v0s, va1" // is this necessary?

Fragment Shader:
"mov oc, fc"

The following my particle is not rendered:

Vertex Shader:
"m44 op, va0, vc0"

Fragment Shader:
"mov oc, fc"

This doesn't make sense to me as line, "mov v0s, va1", shouldn't be needed because the fragment shader get's it's color from constant registers. Why does that line matter?

Thanks!