Enable Secure Network Communication" checkbox in the SAP GUI grayed out (4291117)

If we use Logon Groups, how do we "activate" the "Enable Secure Network Communication" checkbox in the SAP GUI?

By setting the groups instance to the SAP instance that is running the SNC, when you add that group into SAPgui, the SNC Name under advance should already be filled in, and you should just be able to check the "Enable Secure Network Communication" check box. If you do not see the SNC Name, verify that the group is associated to the correct SAP instance, and that the SNC has been enabled correctly by looking in your dev_w0 log.