Graphics Issue in Exported pdf

I am exporting a ZWriter document to pdf, for upload into another service for a biometric digital signature from our clients. We have an inline graphic of our logo at the top left of the page. Everything resolves fine in the pdf when I open it on my desktop, but when it us uploaded the graphic does not resolve, there are pieces but not the whole thing. I have tried the same process using Word, Open Office, Word Perfect and GDocs - all work fine. Any suggestions? The documents are a major part of our workflow, and getting them completely inside Zoho would be major improvement.

Thanks,

Drew