File Saving Error When Using Adobe Acrobat

I have attached here an error message that appears every time I try to save a file using the Adobe Acrobat software.

Here is the error just in case the screenshot isn't clear:
"The document has been saved, however, it could not be converted according to the select standard profile: convert to PDF/A. please use pre flight with the profile “Convert to PDA/A” in order to identify those properties of the document which prevent it from being compliant to this profile. ”
I have been all over the web to find the right solution for this but of no luck.
I hope someone can help me solve my problem.
