We never had a problem with this until beta versions on the New Windows Vista started shipping.  The PKLINK people seem to be out of business, and the "Fix" was to remove the PKLINK and replace it with a different control. Which we have done as of 11-22-06

Our new version  was released on Nov 22nd 2006 and if anyone has this same issue, please contact us. We will work with you on replacing it with our newer "fixed" version.

Best regards

Jim Springer

Below is the result of your feedback form.  It was submitted by
 (alexander750@earthlink.net) on Tuesday, October 24, 2006 at 13:21:51
Customer Name: Mark
Product In Use: Scancat-Lite Plus
Radio In Use: RadioShack PRO-82
Cable In Use: 20-048
Dealer: C.A.T.
Comments: Will not run in Windows Vista RC1 (Build 5600). Scancat appears to install normally, but complains that "PKLINK.OCX is missing or not registered" on launch. PKLINK.OCX is in fact present.
Scancat works OK in 2000 SP4.