Also make sure the call is sealed to the roof of your mouth, the air you are blowing out should be passing between your tounge and the call. Just try to to blow air out your mouth with the call sealed to the roof of your mouth. If the call is sealed to the roof of your mouth, you can't help but make a sound. It probably will be semi-high pitched, but if you can get that far, you are on your way. Then you need tounge pressure to get the yelps and cuts, etc. Make sure the call is properly wet in your mouth, that helps loosen the latex reeds and get a good seal to the roof of your mouth. Above all, keep trying.