My Python script that talks to Interactive Brokers through IBAPI connects fine but stumbles the moment I request market data—quotes come back empty or the call simply hangs. I need someone who really knows the IBAPI event-loop, reqMktData / tickPrice flow, and the quirks of TWS / IB Gateway to trace and eliminate these data-retrieval errors. The codebase is small and isolated to one file plus the usual IBAPI modules, so the task is focused: identify why market-data subscriptions fail, correct the logic (or any mis-used parameters), and hand the fix back fully commented. A quick screenshare or short write-up that explains what broke and how you fixed it will wrap things up. Please be comfortable debugging asynchronous callbacks in Python and validating the solution live against TWS or Gateway.