CheckBoxGruop - SingleSelection

Hi,

i have implemented a checkBoxGroup. I thought that in a group only one value can be selected?

But in my Gruop every CheckBoxField can be selected. I want that only one field can checked and if an other get selected the first field is unselected and the new one is selected.

String[] values = {Value_1,Value_2,Value_3,...}; 
                
             for (int i = 0; i < values.length; i++) { 
                        IWDNodeElement elem = wdContext.nodeNodeName().createElement(); 
                        elem.setAttributeValue("attName", values<i>); 
                        
                        wdContext.nodeName().addElement(elem); 
                }