Sometimes after you make changes to the EnterpriseReferences and re-compile the application, and then go to the EnterpriseASP or the EnterpriseVB application and try to compile, you will get the above compilation error. This error happens because Visual Studio did not copy the new EnterpriseReference DLL file to the local EnterpriseASP and EnterpriseVB (directories even though copylocal=true) for this reference, for some unknown reason. 

There are two ways around this error.

1) Sometimes it could not access the file to copy them because they were active for some reason. Rebooting sometimes clears this condition. You should reboot after you compile the EnterpriseReference project

- or -

2) Copy the Enterprise Reference DLL files into the proper EnterpriseVB and EnterpriseASP directories. You can either manually copy the EnterpriseReference dll's into the bin directories of the EnterpriseASP and EnterpriseVB projects, or you can use the batch file in the EnterpriseReference root directory to copy the files automatically. Please review the batch file before running it.

If you have done the above procedures, and you are 100% certain that the new EnterpriseReference DLL's are in all of the correct EnterpriseVB and EnterpriseASP project directories, then this is a program error in the SomeEntityY dataset and you will have to go back and review your code and fix the change that you made to this dataset.