[Dx4win] wrong heading for a specific call?

[Rick]

I wonder if anyone has an idea why this is going on: I entered the 
callsign "TZ4AM" into the main window on DX4WIN, and it told me the 
heading was 143 degrees. I'm in Minnesota, so this is obviously 
incorrect for TZ. But if I enter any other TZ call, it tells me the 
heading is 78 degrees, which I believe is correct. Why would it show an 
incorrect heading for a specific call?

73, Rick K0XB