I filed an amendment on turbo tax and they said I was owed $900 the IRS sent me only $400, can turbo tax be wrong?

[VolvoGirl]

Did you wait for the first return to fully process and get the first refund or pay the tax due?  The amended return is only for the difference.  

Go by the actual 1040X.  Line 18 should be your original refund amount and line 22 should be your additional refund.  If you paid on your original return it will be on line 16.  If there is an amount owed with the amendment, it will be on line 20.