Got an email saying my return was received and accepted, but when I call IRS they say they haven't received it, or it's not in the system.

I got an email from TurboTax saying that the IRS received and accepted my return (with the subject line : TurboTax Update: Federal Return Accepted - Payment and Voucher Required).  

I received the email Saturday.  Today is the following Monday.  Today I called the IRS about adding the balance owed to an existing installment agreement and they said they haven't received my return.  Is this normal?  How long should I wait before trying to call back?

I owe money so I can't check the Where's My Refund IRS site, but the TurboTax efile status site says 'accepted'.