tf.exe Unable to detrmine the workspace

I am trying to call TF get command via Team Build script. I am getting the following error

Unable to determine the workspace.

Folks over the internet tell that this error is because Team Build cannot find the workspace because it is being called from a directory which is not part of the workspace.

The solution presented is to specify the working directory. I do so. The mappings are ok in Build Definition path as well as in the workspace. But now i get the following error:

Could not find cmd.exe in the current directory . The directory name is invalid.

Kindly help. Thanks

Solved the problem. I added one more binding in my build Definition Workspace Section and referenced files to get/checkin/checkout with the help of variable $(MSBuildSourceDirectory). Meanwhile I ensured that $(SourceDir) is used to specify mapping in the workspace section of my Build Definiton dialog.

_{(source: geekswithblogs.net)}

At the same time i encountered 260-character path limit, so i modified the output directory in build path as described here

_{(source: geekswithblogs.net)}