Wall Power Source for UR22 mkii Not Working


Is it possible to run the UR22 mkii just from the wall rather than the USB connection to the laptop?

I have my monitors connected to the UR22 and my portable cd player through the input 2. This works fine when I have the UR22 connected via USB to the laptop but when I disconnect the USB and insert a 5V DC external power supply and turn the power source switch towards the 5V DC port nothing comes through the speakers. The external power adaptor is 5V DC 1000mA

Am i missing something here? Should the UR22 be able to run direct from the wall? Or is either the power supply or ur22 malfunctioning?