It means the compiler failed to generate the GPU code for some reason. Can you post the full output from your compile? There should be some error messages above this one that will tell us why the failure occurred.
My best guess is that you have a installation or configuration issue such as not installing the CUDA Toolkit that accompanies the PGI installation.
Does this mean that the trial version cannot use gpu acceleration?
No. The trial licenses enables all GPU features for the 15 day trial period.