gps keys

I have been able to program all the buttons on the default GPS in fs9,except for the 'clr' button. It works fine when I mouse click it,but trying to assign it to a keystroke does nothing.It shows up properly in the cfg. file. Would the only answer be to purchase FSUIPC,or does anyone know of a workaround, and if if it does indeed work in FSUIPC.Thanks for the help.skip d