speed HF spindle and WinPC-NC

I am having trouble setting the speed of the spindle. On manual control it will reach 99% speed but with system control it only reaches 45%.
Speed set in Gcode program is S20000, setting on tool page is 20000, on data format page not checked to ignore speed in file, on speed page default is set to 20000, on machine parameter page max speed set to 20000, on parameter measure dynamic speed set to 30, on macro page spindle speed set to 20000.

I have run out of ideas of where to go to get the machine to run to the max spindle speed, any help please.