Hi Thayne,
There are occasional errors that I see, but 75% seems quite low. First, this is a CMOS input, so your signal levels seem ok. In HSDCPro, first turn off the trigger mode in the Data Capture Options > Trigger Option. Then verify that regular capture is working consistently. Assuming that the trigger is going to J11 of the TSW1400 directly with no T connections, re-enable the trigger mode and also choose "arm on next capture button press" . Then, press the capture button and it should capture data. If it says "No trigger occured", then this is most likely the Hw trigger signal.
By the way, Which ADC is this?
Thanks,
Chuck Smyth