Linking to a DLL

I am new to QT and I have a (probably stupid) question. I hope this is the proper place to ask this.

I created a project for my main app, and a separate project for a QT dll which the main app is going to use. In the project settings, I set the Dependencies of the main app to include my library project. But when I build, it is unable to link to the library functions.

What am I doing wrong?

Thanks

It will probably be best if you could post screen shot of the main project and subproject properties you set.
Also, please post the build output you got.