.NET DLL loading issue in another application

It looks like an issue unconnected with the DLLs. In our application during startup we use the build date string (which we get using: echo %date% %time% > "$(ProjectDir)\Resources\BuildDate.txt") to check for the validity of the trial period. Apparently the check is failing for some reason always, even though we are using the resource manager to load the string after using the proper culture info and even when it is built within the same time culture. As a quick fix, we have commented out the check and found out that the load issue is not there.

But as followup, can anyone let us know how to check this validity? We need to keep track of the build date and the take the difference with current date to determine the elapsed time.