Coyotes are very smart and difficult to call in. Wind is your biggest factor. If theyre yipping and calling they either know the call you are using or theyve scented you out.
Dont get discouraged. It took me around 20 stands before i got one to come in. Coyotes know their area well. Keep experimenting with different calls and eventually you will find something that peaks their interest.
I use E calls almost exclusively. I find the issue I have with reed calls is getting the volume just right. If youre too loud you will spook them.
Keep the wind in front of you.