E-Filing Delaware State Return with attachment

[U824731]

I cannot e-file a Delaware state return with a pdf attachment.  Pro Series responds with a red error indicating the return needs to be mailed. The attachment is another state's return as proof for the Tax Paid to Other States.  Any way to overcome the error?  

[IRonMaN]

You have to select the type of pdf attachment when you add the attachment to the return.  Did you accidentally label the pdf as something other than the other state return?  Also, you did add the attachment to the federal return instead of the state you are trying to get the credit from?  If everything above is ok, try deleting the attachment and add a new attachment.