Problem debugging 64 bit application in vc++.net

Hi,

I have problem debugging 64 bit application in vc++.net

i have the following installed elements.

1) OS :- Microsoft Windows Server 2003 [Standard Edition x64 Service Pack 1]

2)Microsoft Development Environment 2003 ver7.1

3) Microsoft .NET Framework 1.1

4)Microsoft Platform SDK for Windows Server 2003 SP1

i builded my VERY SIMPLE app in 64 bit mode by invoking the IDE through Platform SDK build environment using "Set Win Svr 2003 x64 Build Env (Debug)" option.

i successfully builded my application to create 64 bit EXE after modifying the necessary project settings.
My Application correctly displays the sizeof(pointer) as 8 bytes which
confirms my settings and requirments.

...But When I Try To Debug My App I Get The Following Message

"unable to start debugging
unable to start program "verysimple.exe"
the specified file is an unrecognised or unsupported binary format..
"
well i could not figure out the problem.

if vc++.net can create binary executable that runs successfully then
why do i get the above message when i attempt to debug the same app.
please help me..