I have to really dig deep into my memory, but if I am not mistaken it is because your CPU is not not recognized by speed-step centrino.
Your {CPU, model, stepping} is {6, 11, 1) whereas speedstep-centrino recognizes {6, 9, 5} and {6, 13, *} That was at least the case in my version of the file.
You can check
my page on the installation of speedstep on my laptop. Also check the external links in that chapter.
I assume you have to define your CPU in the speedstep source file, insert the proper {CPU, model, stepping} tuple, insert the correct voltage/frequency pairs and recompile the module. Be careful what you do though.
jlinkels