Quote from Businessman:
I use the IB API for my own bracket orders.
I fire dozens of bracket orders at TWS via the API each day.
I find that sometimes (about 1 in 50) bracket orders do not always transmit properly.. some parts of the bracket order are shown in TWS with the 'T' status.
I reported this to IB but it didnt get anywhere as they were unable to reproduce it.
I have created a work around in my code that reduces the occurence of this for me (basically slowing down the speed at which i fire the legs of a braket order at TWS using 'sleeps' in my code).
I've never noticed a problem (using zeroline trader and lots of bracket orders every day on ib live account)
Two things you could do that might improve things by increasing TWS's performance and system priority -
1) Change your TWS load sequence to use the -server java vm which is faster than the -client (see the thread here about running java faster).
2) Download Prio from http://www.prnwatch.com/ . Then put your TWS priority to high and (maybe) your bracket trader priority to above normal.
THESE ARE NON-STANDARD CHANGES SO DON'T BLAME IB IF YOU HAVE PROBLEMS ! (use in direct proportion to your own knowledge and skills)