HTB class parameter change

HI,

I am trying to change the rate parameter of HTB class by using this
code from within one of my functions :

 struct htb_class *cl;
 cl=htb_find(number,q);

 cl->rate->rate.rate = NEW_RATE_VALUE;

 TC shows the correct values, but the traffic rate doesn't change a bit.
 Does anyboyd have any idea what am I doing wrong ? Maybe there would
be a faster way by sending a netlink  message ?

Piotrek