I cant go to 192KHZ

[KINGDRAGON]

Hi there, does anyone know why i can't sync at 192KHZ my 3 apogee's converters with protools 8/HD2?

I use the internal clock of Apogee DA-16x (has the same clock machine with big ben) and via word clock connects Rosetta 800 and Rosetta 200. I switch the Sample rates from the ProTools every time i want to create a new project iwith new rate. (44.1 or 48 or 96 etc).

All the rates works fine (all the system looks stable until the 176.4 and 192 !!!
The Rosetta says that connects to this rate but never did it !!!

So the system hang when call the 176.4 or 192 , so i left the whole system sync to the 96KHZ!

where is the wrong?
thanks
george