Hi Uwe,

Thanks a lot for your reply. Following it, I checked with DepedencyWalker the dependencies of qwtpolard.dll and saw that
it depended on qwt.dll (instead of qwtd.dll). The reason is the following : Previously, in order to compile the qwtpolar libraries
under QtCreator I had to add qwt paths (lib and include) and library name to the qwtpolar/src/src.pro file and forgot to make
the distinction between release and debug mode.

When I do it in the right way (using CONFIG(debug, debug|release) ... ) it works perfectly : qwtpolard.dll depends on qwtd.dll
and my application runs in both modes.

The question is now : why do I have to add the dependencies to qwt (lib and include paths) when I try to compile qwtpolar
whereas I use the default .pro files delivered with qwtpolar1.1.1 ?

Thanks again.