Demultiplexer needs data to parse it and configure output pins. So NWSource should be configured to receive data. If there is no data on NWSource there should be no output pins on demuxer. You should not start and stop graph, but you can simply wait when these pins appear.
First of all verify if NWSource is configured correctly.
You can see property page-> Advanced settings.
If you see "Data not available" it means that NWSource doesn't receive data and doesn't put it to demuxer.
If you see "Ok. Data present" it means that everything should work.
If I do need to configure something, what and how?
You can change parameters on property page.