Unknown attribute: "iUv"

[kxygk]

Thanks for the slick Cinder block. I've been playing around with it, and during runs I noticed that I get the following warning

|warning| cinder::gl::GlslProg::GlslProg(const cinder::gl::GlslProg::Format &)[608] Unknown attribute: "iUv"

I'm looking at your shader, and it seems fine to me - but I'm not expert