MFC Dialog Problem

Im having a bit of an issue with one of my MFC dialogs. After declaring a variable of the dialog class, it gets NULL... like this.

CMyDialog dlg;

so my progam crashes as soon as I use i etc..
m_dlg = &dlg;

Its a visual studio 2k3 generated dialog. Which wa working initially.

Could anyone please tell me if they have any idea what the issue might be.
The constructor is called fine, so im not sure why it would be a null object.

Thanks.

ok, i fixed it.

Pretty stupid problem really.
When I was compiling with VS2k3, it wasn't remaking my .obj files, so it wasn't detecting that there were link issues such as redefining a variable.

Just clearing my debug folder showed me the link errors next compile.