[amibroker] TRENDLINE BREAK ALERTS

["osgem_2006" <osgem_2006@xxxxxxxxxxx>]

i want to write formula for alert of trendline break on an indicator.
I wrote the following 
// Trendline Alerts
 Sell = Cross( CCI 14, Study( "SU" ),CCI 14,GetChartID());
when i tried to scan a symbol I get syntax error , error 31,syntax 
error, expecting '('

please help me to write the correct code.

thanks
osgem_2006