Event unsubscription in another file

Question

hi,
I am working in a window project, which has a reference of a utility project that contains generic methods. for example one for binding combobox with dataset at runtime-:

 

ComboUtils.FillComboBox(cmbSubRegister, 
RGMaster.GetRegisterByParentID(Convert.ToInt32(cmbRegister.SelectedValue), false), 
true, "RegisterName", "RegisterID");

The ComboUtils.Fillcombobox function has follwoing definition

 

public static void 
FillComboBox(ComboBox cmb, object obj, 
bool valFieldRequired, string dispField, string valField) { 

if (obj.GetType().ToString() == "System.Data.DataSet")

{ 

cmb.DisplayMember = dispField;

if (valFieldRequired)

cmb.ValueMember = valField; 

cmb.DataSource = ((DataSet)obj).Tables[0];

}

Now the problem is that selectedindex changed event gets fired.
I tried to unsubscribe selectedindexchanged event from combobox object being passed and later resusbscribe after datasource has been set but i just can't get reference of the event handler in this file.
-: EventHandler ev=cmb.SelectedIndexChanged gives error that it can only be at the left hand side of += operator.
Can somebody tell me how to do that?
Please.. thanks in advance.