Can't debug c++ project because unable to static library start program *.lib

I'm using a library (Astro.lib) which i've built without problems (i guess this is a release build).

I've also built a project which references the library (it runs as a release exe fine) but i can't debug the project because i get the message 'unable to start program 'Astro.lib'.

If i try to debug the lib then i get the same error, so I guess its something to do with not building for debug my lib but not sure how to modify.

I've tried changing the properties pages using MSDN info but not sure i'm addressing the correct problem. What changes should i make to the properties pages of the library of linking project?

Thanks in advance

I've also built a project which references the library

That's the project you want to debug. You probably just have the wrong project selected as the startup project of your solution. It is marked in bold type in the Solution Explorer window.

Right-click the project that uses the library and select "Set as StartUp Project"