First, look to what the terms of your representation and/or employment had been--if those terms address this situation, then they will control.Second, as a more general principal, if the property sold to someone you had shown it to previously, you may be able to assert a  claim for  a portion of the commission based on the fact you had shown it to the ultimate buyer. But if it sold to someone you had not shown it  to, then no--the fact that you have performed work on a property does not, by itself, guaranty you to compensation or a share of the commission.