This happens because the students' name does not match. This could be that there is a different spelling in the last names, first name, or a nickname. The Candidate's name must match exactly in order for it to display in the dropdown for Inquiry Years in the user's record. Otherwise, this will create a new user.

On Step 3 of the Create an Inquiry it will say New User or show the existing 
user. If you do not see Show the Existing User then you must have a spelling error in the name which means the users do not match.