[rules-users] Rule Compilation error : The Field ... is not visible

Hi All , I am sure there must be a silly mistake but i am not able to find out , please help me as what is wrong in below rule package Test import com.abc.api.document.Document import com.abc.api.line.LineItem rule "split line item" when $item : LineItem( grossAmount > 1000 ) then modify( $item ) { grossAmount=500 }; end 11:35:23,318 ERROR [] Rule Compilation error : [Rule name='split line item'] Test/Rule_split_line_item_0.java (7:565) : *The field LineItem.grossAmount is not visible* Thanks, Ashish