Problem with active object - CTimer - SetActive()

Hi all,

I want to make this timer work but it crashes on SetActive() command.

Class symbian_timer_helper is derived from : public CTimer. It crashes but does not even run RunL() command of CTimer! It does not even start the timer if I remove SetActive().

Here is the code:

void symbian_timer_helper::base_constructL()
{
CTimer::ConstructL() ;
}

symbian_timer_helper * symbian_timer_helper::constructL()
{
symbian_timer_helper * self = new (ELeave) symbian_timer_helper();
CleanupStack::PushL(self);
self->base_constructL() ;
CleanupStack::Pop();
CActiveScheduler::Add(self) ; // did I start the active scheduler with this?
return self;
}

After this start is called:

void symbian_timer_helper::start(int timeout_value,
timer_expiry_handler & i_timeout_handler)
{
timeout_handler = (& i_timeout_handler) ;
TTimeIntervalMicroSeconds32 timeout_interval((TInt)timeout_value) ;

After(timeout_interval) ;

SetActive() ; // mega-crash but why???
}

Where ussualy problems are with SetActive() command?
Just to say I'm a beginner in Symbian, btw.

Thanx very much in advance !!