Hi czheng,
Would you be able to provide us with the ANT log from both your mac and your PC? This would give us a lot more insight into what is happening, and might help us come up with a solution to this issue.
If you do not already have ant logging enabled in your application, it is highly recommended that you do. ANT logs are a record of all of the serial communication between the host and ANT, and are a great way to debug applications. DEMO_LIB in the windows library package shows how to enable debug logging. In particular pay attention to the calls to DSIDebug::SetDebug.
Cheers,
Kassandra