Adjusting sales price for hours on a project in Professional Services Automation

Can anyone tell me how the FUNCTIONS > ADJUSTMENT function is supposed to work in PSA?   

I am trying to mark up - OR - mark down the sales price on hours posted to the project but am getting very odd results.   I want to markup the sales price for hours by 50% - so I am selecting MARKUP PCT in the Sales Price drop down, then entering 50.00 in the Markup pct box.  Clicking OK but getting nothing close to a 50% upward adjustment of the sales price....

Any help you can provide is greatly appreciated..

Thanks

Joe