I had previously ran into an issue where the crontab did not open the file to edit due an issue with the default editor path. This can be checked by just trying to open the vi editor from the prompt. If you run into issues in opening a file using 'vi', then crontab -e will not work.
Here is a different case, where 'crontab -e' throws a number back to the screen and does nothing. Example:
This number is differing for each user...