Well that error means the compiler can't find the correct dll for the command you are using.
When you open up My Computer (from the desktop or Start menu), double-click on Local Disk (C

. Do you now see a folder named 'Dark Basic Professional'? If so, open it (double-click on it)
If not, double-click on the folder 'Program Files', then double-click 'Dark Basic Software', then double-click 'Dark Basic Professional'. This is your DBpro installation folder.
If you've now opened your DBpro installation folder, double-click on 'Compiler' then 'plugins-user'. You should see DBP_NETLIB or DBP_NETLIB.dll inside.
If this file is not inside, copy it there from wherever you downloaded it to (right-click on DBP_NETLIB.dll, wherever it is, the choose copy. Then right-click in the user-plugins folder and choose paste).
If DBP_NETLIB.dll is inside your 'user-plugins' folder, then it should be installed.
-Xol