considering consrtaints on output of mpctool in matlab?

i am using mpctool in matlab and need to consider constraint on output and input.my input accepts constraint between -300 to 300,but output doesn't accept constraint between -1.3 to 1.3.my output figure is between -0.5*10^4 to 0.5*10^4.it is really simple but i don't know why output doesn't accept constraint but input is OK? how i have to fix this?