Post-build event copy not working

I have a post-build event to copy a .dll from one project to another on successful build using the following command:

copy $(TargetPath) ....\MainProject\bin

This works fine on my local machine, but it appears to be failing on the build server because when building the MainProject I receive the following:

warning MSB3245: Could not resolve this reference. Could not locate the assembly "Project2". Check to make sure the as开发者_StackOverflow中文版sembly exists on disk. If this reference is required by your code, you may get compilation errors.

Has anyone experienced similar issues with the copy command in a post-build event?

That warning isn't from the Copy task, it is from the build of a project. Crank up the diagnostic level and log to a file (/fl /flp:v=diag;logfile=diag.txt) to see where the warning is actually coming from.