Are the criteria values numeric? If so, the single quotes may be the problem
DLookUp("VAC","CALC","[CALC].[AL Corr Std Hours] = " & [Example].[AL Corr Std Hours] & "' And [CALC].[FLSA OT] = " & [Example].[FLSA OT] & "'")
EDIT - forgot to mention that the first one shouldn't enclose the AND operator regardless. So regardless if the values are text or numeric, the quotation placements are incorrect. Let us know what the value types are if you need more help.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.