what are the buttons to use the power ups in star wars battlefront

Hi been playing the beta of star wars battlefront and i have been through the whole keyboard ...and i cannot find the key to use or activate the power ups xwings walkers etc etc i use the E key to claim it but i cant activate it...it most frustrating because i've seen other people use them ???  do i need a joy pad or something ??  there are no key bindings even listed to use a power up

any suggestions ..please