Need Help Onyx and Coreldraw

I'm new to Onyx and I I can't get it to recognize the layers in my Corel generated pdf file. I'm trying to create a spot color to print white, but Onyx will only see the top layer. Is there something I'm doing wrong? Thanks!

 

Thanks so much! I need white behind the image, as well as needing white text reversed out of the inside of a logo. This function does put white behind the image, but doesn't print the white text. How can I get the white text to print?

 

Ok, I got it. Simply assign the white a spot color on the same layer and it works in conjunction with the Onyx spot enabled. Thanks again!