You might want to post your VBA code that you are using to create and run your SQL statements.
Also note that you might need some text and date qualifiers in your code.
Here is one way to approach your situation. Manually create and run an example query (that reflects what you are are trying to do) to insert hard-coded values, like the one you referenced, i.e.
Code:
INSERT INTO tblCustomers VALUES (1, Kelly, 'Jill', '555-1040', 'someone@microsoft.com')
Test the SQL code, and confirm that it works (if it does not, modify it until it does).
Then, using VBA, try to program and create the same statement using your variables (text and combo boxes from your form).
Instead of attempting to run that SQL statement, first spit it out into a Message Box so you can see exactly what it is building. Compare the structure to the example you got working. Is it structured the same? Does it have all necessary text and date qualifiers?
One you have to the point where it matches, then try running it.