I am not able e-file. I get the error message; 'we can't e-file your return, we are unable to locate the attachment at/attachment/form7203.pdf.' Form 7203 is completed

My form 7203 is completed and available for viewing under forms, so what is the problem?  how do I find where to attach?  I could print out form 7203 and create a pdf file, but where do I put it to so TT can find it?  thanks