Before the message, you should see: "Checking for existence: ...".
Make sure the dll exists in the place C::B looks for it.
Ok, I did that.
In the build log window, "Checking for existence:" is displayed and the name of the DLL was incorrect.
I didn't fully understand to begin with as I expecting to see a dialog box with "Checking the existence", but then I saw it in the build log.
So you have lead me to the solution of the problem. Wollow in the satisfication that you've solved my quite silly config problem. Unfortunately, I'm using a project created by someone else.
An answer like "Check under Project->Properties, select Build targets tab and verify the output file name is correct" would have lead me to the solution much faster though.
I suppose, it is fair to assume that you thought I created the project myself, so you have probably assumed I knew more about configuration than I actually did.
Thanks for your help and it wasn't a waste of time. Perhaps someone else will have the same trouble someday and they can read this thread