This method fails if the line is not a group line. Group classes are used to identify group lines used for special purposes. All group lines with the same class share the same list of associated channels. As of v6.3, if a group line has no class defined, then ALL channels are assumed to be associated with it. This means that a group class should only be defined when you wish to associate a subset of the available channels to group line.

public void SetGroupClass(
	int i1,
	string str2
)

Public Sub SetGroupClass ( 
	i1 As Integer,
	str2 As String
)

public:
void SetGroupClass(
	int i1, 
	String^ str2
)

member SetGroupClass : 
        i1 : int * 
        str2 : string -> unit