You missed the single quotes when using the variable. You need:
.Source = "SELECT Year, Period, BatchRef, TransRef, LedgerCode, Contract, Description, Stockno, Quantity, Unit, Rate, Debit, Credit, Store, SYSDATE FROM TRANSACTIONS WHERE  (Store = '" & StorNum & "') AND (TransType = 'STB') AND (Allocation = 'Contracts') ORDER BY TransRef, Stockno"