ComboBox, Control, on Worksheet: MatchRequired NOT working

Trying to keep typing functionality but limit user's typing to required items in Listbox

MatchRequired is not working for some reason and I'm getting out of range error. I'm assuming the built in error handling is reverting value to 0 which throws of the code, but not sure. Before I break something, could use some help? Still learning VBA, not the best at coding in error handling.

Reporting Tab

TestsStart
TestsEnd

if type value TestsStart < TestsEnd = Problem
if type value not in boxes = Problem

Help?

help please?

If Sheet5.TestsStart.ListIndex <> -1 Then
Code
End If