When is this a no call?

[lmeadski]

A1 comes down the lane and leaves his feet for a shot. At some point, B2 steps in front to draw a charge. After the contact, both players are on the hardwood. I purposely left out "the details" to hear your responses on what circumstances must be present for the NO CALL. I had this situation tonight and made no call. BOTH coaches came unglued! One wanted a charge, one wanted a block. When do you all remain mute on such a situation?