The list of PageGate modules that are enabled and available are listed here. Modules that are not highlighted are not available. Modules not checked are not enabled for this group. For example, if the GetAscii module isn't enabled for your group, the GetAscii module will not be able to send this group any messages.
If an Interface is not available and it should be, please make sure that the Interface is enabled both in the Program Settings and in the Interface Settings.