cannot convert method group non delegate type list string

Trying to populate the list string from list string method from products classes' method, got this error public static List<string> GetProductSupplierCode_ByProductANDSupplierID(long lgProductID, long lgSupplierID)     { ... List<string> lstpscode = new List<string>();                         lstpscode =  Products.GetProductSupplierCode_ByProductANDSupplierID; ...