In Acrobat XI Pro, after placing a watermark on a PDF, applying an A / Web certificate, then saving as a PDF-A, the text in the document becomes unsearchable.

After adding a watermark in Acrobat XI Pro, and A/Web certifying and saving as a PDF-A, the text in the PDF becomes unsearchable, and it seems that the pages were flattened.  Under save settings, I can see radio boxes that I can uncheck to make sure the pages don't become flattened. This results in a error, and the PDF does not get it's A/Web certification.  Is this a glitch?  I can search text in an A/Web certified document with no watermark, just fine.  I can search text in a document with a watermark and no A/Web certification, just fine.  Just not with both items applied.  Why is the watermark causing a conflict?  Is there a way to fix or get around this?

Thanks!