PTO parameter settings

[pfk]

We are trying to adjust the settings for the PTO ramp rate on a 2008 ISX CM871.
when we set the ramp rate to 50, it will work when we manually raise the rpm by holding the set/resume button; however if we hit the button one time and allow the ecm to bring it to the set amount of 1100 rpm, it instantly raises it to that amount instead of ramping up slowly.

We made the same settings to the truck sitting in the next bay (2012 ISX15 CM 2250) and the ramp rate worked as desired in both scenarios.

Is the CM871 not capable of working in this manner or did I miss something while changing the parameters?

thanks in advance