pwm hpwm difference?

Hi,

I have a line in my program, " pwm portc.1,255,100 ". And I read 5.0V. on PortC.1.(I am using Proteus.). But, When I changed this line to " hpwm 1,255,10000 ", I read about 3.0V. on PortC.1. I use 16f877A and 20Mhz. crystal. How can I read 5.0V. on PortC.1 by using HPWM command?

Thanks.