When youre in the client return with the SC state open on the screen, top menu bar, click Efile > Attach PDF

(you'll have to have a pdf of the other state return available to attach, I generally print a copy and run it though my scanner)

Thank you. Already did that, well before coming to this resource (I was SEVERELY limited in number of characters I could use in the question). Any other ideas? The check box within the SC return even AGREES that the MI return is attached.... when I click on the error message, it just sends me there, but it's already been done. I welcome any other ideas. 

Thank you!

YOU ARE THE BOMB!!!!! (Do people still say that??!?) I made that simple change, and the error message cleared!! It had been "Other", not Other State. I just e-filed it, hopefully successfully (we'll know tomorrow for sure). Whew!!! THANK YOU SO MUCH!!!!!