Why doesn't my four-way gang valve work?
If you are using a gang valve or T-splitter to share one air pump with multiple devices, sometimes air does not travel down all of the outlets. One of two things could be happening. In the first case, your pump is not strong enough to push air into more than one outlet. In the second case, the air always chooses the path of least resistance, so you need to use air valves on each path to ensure that air reaches all the devices.