Instructions
Turn on both the PS2 wireless controller and the wireless transmitter. The wireless transmitter must be powered on (some turn on automatically after connecting them to your console, while others require you to flip a power switch) as well as your controller for the controller to communicate with the system.
Stay within 30 feet of your console. Most wireless PlayStation 2 controller's only have a range of about 30 feet. This means that if you move outside this range, the controller will not work. Likewise, try to stay in the same room as your console as certain brands and models have a hard time transmitting through walls and other solid objects.
Replace the batteries in your wireless PlayStation 2 controller. Most wireless PS2 controllers take two or more AA- or AAA-sized batteries in order to operate. If your controller has worked in the past but is no longer working, this is an indication that the batteries have depleted. Replace them and attempt to use your controller again.