I have posted in the VB section, but since then have experimented further. Using vbstudio I have been able to observe the errors and it seems that the driver is being upset by the call parameter decleration, I have checked against the documentation and it seems to be OK - the error seems to be in the dll and I get a message about an unreleased global in the dll at line 1439. Can you supply a corrected VB decleration module (the one in the VB demo is incomplete and I suspect the type declerations may not be accurate) for either vb6 or vb2005. Working in 2005 would seem better as the required types for calling the dll are implemented from vb. I need something rather urgently as I am struggling to get the unit working reliably in any sort of VB programming environment.