@HeatherPrice -
Ok. without seeing the actual data (which I know you can't share) it would be tough to figure out what the issue is. The only thing I can suggest now would be to look at the csv file in a text editor and see if there are extra spaces that may (I really don't know) be in fields that are causing issues.
i.e. if a line is: stude_name,45676 , 60 , where there are spaces after 45676 and before and after 60, that could be an issue - I would think not, but who knows.
Another possible issue would be certain line terminations characters that are present. If you have access to vi or emacs, text line editors on Linux systems you can see strange characters that would have to be removed. You might also want to open the csv file in notepad++ (much better than notepad) and save it under a different name-I believe there are options to change how the file is saved to avoid some of the strange line ending characters.
Lastly, I would just work with a file that has been whittled down to just the main information and one assignment grade.