Access 2003 Question

I've created a database where I can log different IT issues in order to track and turn into the CEO quarterly. 90% of it works great, the problem is that I'm getting Error 3101 The Microsoft Jet database engine cannot find a record in the table with key matching field(s) .

I'm using a combo box to pull data from a table.

Here's the SQL View script:
SELECT NewContacts.ID, NewContacts.[First Name] & " " & NewContacts.[Last Name] AS Expr1
FROM NewContacts
ORDER BY NewContacts.[Last Name] DESC;

I'm lost as to what to do, there are two contacts in the table and it can save to one, and not the other. Please help!