Cannot hold current call and answer an incoming call

[Dana1393]

I have a jailbroken 3g iphone, and I've noticed that I cannot hold my current call with someone and answer an incoming call. Does anyone know why this is happening?! But I CAN make another call while I'm on a current call, it just won't let me press the "hold call and answer" button when there is an incoming call. And i already tried restoring and jailbreaking again, but that didnt fix anything. Any help would be greatly appreciated. :confused:I'm clueless about this.