We have just increased our clock rates on our 2 WICs in our 2611xm router from 2600000 to 5300000 after we have had a problem with slow internet lines but if we want to push them upto 7000000 (the highest), we get an error stating "Insuffcient clockrates, available (including current clock rate) = 5700000 bps."

How do i get round this so i can make both WICs use the 7000000 bps setting?