Sorry I'm replying so late,

my $OpenTopic      = new Win32::API
("pmdbf32", "OpenTopic", [P, P], N);
[download]

That is wrong, bare letters aren't letters but subs to run. Put single quotes around the parameter letter codes. And add a ".dll" to dll file name. You dont have to, it makes code easier to read.

are you running on 64 bit or 32 bit windows? What the the C prototype of that OpenTopic function?