Ulink2 SW Clock Frequency

I'm using Keil Debugger SW adapter and wanting to run this at 10MHz clock rate. I set the Max Clock in the target debug setup to 10MHz, but when I run the debug session and monitor the SWCLK frequency on the scope it is not 10 MHz but around 1.4MHz and the clock signal is not 50% duty cycle. Can anyone tell me why it is not 10MHz? Thanks.