Combining two data sets

Hi All,
This has been an excellent forum helping me streamline my department, I have another question.

I have class lists and raw exam data I want to copy the exam data to the corrosponding students. Not all students that have are in the class list have data for the exam. I have been looking at Vlookup but cant seem to get away from #Ref error. I have attached an example.

What I want to do is copy the UMS score and grade from the Exam Data sheet over to the class list in Column D & E.

Many thanks for any help