Did you have some sort of mix up as to who could claim a dependent and now someone's return is being rejected, while the other parent is amending? You do not have time to wait for an amended return to be processed--it takes months for the IRS to process an amended return. The "rejected" return now has to be printed and mailed--it cannot be e-filed. Remember when you mail a return, include copies of W-2's etc and attach to the return.
And a suggestion:
To send your tax return by mail and get a receipt to see that the IRS received it:
https://www.usps.com/taxes/welcome.htm