Are you using latest version? If not, please upgrade Full Convert first as we don't support old version.

If error appears in the latest version, send us bug report from the application itself. You will see a link in the Conversion Summary dialog, under Errors tab. We will get back to you soon.

If you are using trial version, first send a bug report and immediately after that open a support ticket with problem description. This is needed as for trial version we might not have your email address.