rvk

Hard to say what could be the cause without example-source of DLL and calling procedure.

On 64 bit it worked for me but I did't have any scan-sources. WIA sources are 32-bit and not visible in 64 bit for me. Installing the VueScan gave me a 64 bit source. What Delphi version do you use? Are you using VLC of FMX? Did you try the DelphiTwain\examples\VCL2\DelphiTwainDemo2 example? (which worked for me on 64 bit)

So you provided a "bad value" Here it works fine with VueScan as 64 bit scan-sourcedriver. What/which scannerdriver did you try/use?

But that's how we recognize the administrators 😁 (although that information is also under the avatar-hoover.) I find that information useful to see in one glance. Hovering over the avatar hides it too much for me. +1 for the other suggestions although I wonder how much the layout can be changed from the default via themes (because this is based on standard forumsoftware). Ah well, there is always greasemonkey