DW Spectrum can perform basic diagnostics to determine why a camera is offline. If you cannot fix the problem yourself, it is important to run a diagnostic test prior to contacting support, and provide them with the results.
A camera that is offline will be have an offline icon (
) in the Resource Tree and will display NO SIGNAL in layout. Diagnostics can be invoked by pressing the Diagnostics button on the item:

Once diagnosis is complete, the analysis and recommended actions will be displayed:

Follow the instructions to resolve the issue. If unsuccessful, contact support (see "Contacting Support").
IMPORTANT: Make sure to click Copy to Clipboard and paste the data into your message prior to sending it to support.