Could you please copy paste the entire error message? That would be useful for helping you. :)
Btw, do you hve any third party icons added? Tried packaging after removing those?

Thanks phoneyguy for the solution.

The layers view trick that you found on the internet was infact a workaround in older Carbide.ui versions.
The best way to make any thing transparent is to...

Carbide.ui (Symbian) v 4.0 is now released. Go grab your copy from bit.ly/fmLj44