Four weeks is plenty of time to allow for a check to clear. If it hasn't been received by whomever you sent it to, call your bank and inform them. You may need to complete some forms and get a bond (the bank handles this) in order to have the check reissued. Because cashier's checks are "as good as cash", there are restrictions imposed on reissuing them, one being all but certain that the old check won't appear and be cashed.
Published on BankingQuestions.com 9/22/10