problem making a data call

ok. I'm using my cell phone, a Nokia 7160, with the Ositech KOH card. i've setup the software part ok, but when I try dialing, the first thing that happens on my phone is I get a "data call ended" message, and then a "no dial tone" message pops up on my laptop. So I took off both messages and tried again: same result.

I was able to dial once, but not again. What's weird though, is that even after I unplug the cable, I keep getting the data call ended message popping up all the time, ending only when I turn off the phone.

Any idea what's going on? Thanks.