NT cancelled ATM orders after bracket entry

[MTaylor123]

I originally had a bracket of two ATM orders placed oco. I would go short at 117.80 or long at 120.50. When I got filled, my short should have created a target and a stop loss. The stop loss was to be at 120.50. From what I could tell from the log, this caused a problem because of the original order to go long was at 120.50. Am I correct or was there another reason? NT cancelled my target and stop, and I had to re-enter them. No harm done, but I'd like to know what happened. Here are my log entries for that time period.

Order='5760992/32181!Dorman!ProActive' Name='Target1' New State=Working Instrument='KC 03-09' Action=Buy Limit price=101.95 Stop price=0 Quantity=1 Type=Limit Filled=0 Fill price=0 Error=NoError Native error='' Order='5760992/32181!Dorman!ProActive' Name='Target1' New State=Accepted Instrument='KC 03-09' Action=Buy Limit price=101.95 Stop price=0 Quantity=1 Type=Limit Filled=0 Fill price=0 Error=NoError Native error='' TE_invalidStopAndLimitPriceDifference Affected Order: Buy 1 StopLimit @ 120.5 x 121.5 Order='5760991/32181!Dorman!ProActive' Name='Stop1' New State=Rejected Instrument='KC 03-09' Action=Buy Limit price=121.5 Stop price=120.5 Quantity=1 Type=StopLimit Filled=0 Fill price=0 Error=OrderRejected Native error='TE_invalidStopAndLimitPriceDifference' Order='5760991/32181!Dorman!ProActive' Name='Stop1' New State=Accepted Instrument='KC 03-09' Action=Buy Limit price=121.5 Stop price=120.5 Quantity=1 Type=StopLimit Filled=0 Fill price=0 Error=NoError Native error='' Order='5756182/32181!Dorman!ProActive' Name='Entry' New State=Cancelled Instrument='KC 03-09' Action=Buy Limit price=120.65 Stop price=120.55 Quantity=1 Type=StopLimit Filled=0 Fill price=0 Error=NoError Native error='' Order='e0bdc7425152485ea2a4e8575ac75a92/32181!Dorman!ProActive' Name='Target1' New State=PendingSubmit Instrument='KC 03-09' Action=Buy Limit price=101.95 Stop price=0 Quantity=1 Type=Limit Filled=0 Fill price=0 Error=NoError Native error='' Order='432d22ead37b45cb98f743f23ad3f131/32181!Dorman!ProActive' Name='Stop1' New State=PendingSubmit Instrument='KC 03-09' Action=Buy Limit price=121.5 Stop price=120.5 Quantity=1 Type=StopLimit Filled=0 Fill price=0 Error=NoError Native error='' Instrument='KC 03-09' Account='32181!Dorman!ProActive' Avg price=117.8 Quantity=1 Market position=Short Operation=Insert Currency=UsDollar Execution='8729896' Instrument='KC 03-09' Account='32181!Dorman!ProActive' Exchange=Nybot Price=117.8 Quantity=1 Market position=Short Operation=Insert Order='5756165' Time='2/3/2009 9:53:22 AM' Order='5756182/32181!Dorman!ProActive' Name='Entry' New State=PendingCancel Instrument='KC 03-09' Action=Buy Limit price=120.65 Stop price=120.55 Quantity=1 Type=StopLimit Filled=0 Fill price=0 Error=NoError Native error='' Order='5756165/32181!Dorman!ProActive' Name='Entry' New State=Filled Instrument='KC 03-09' Action=Sell Limit price=117.75 Stop price=117.85 Quantity=1 Type=StopLimit Filled=1 Fill price=117.8 Error=NoError Native error=''