Hi,
A few things to look for:
1. The MIDI playback device - in Staff/Setup, check the Device and make sure it is a device that is "on" for your setup. Also check the Bank, which typically should be "000,000 General MIDI" unless you have a special setup.
2. Volume - make sure the volume level of the staff is set around the same value or higher as the other staves. You can check this in the Staff/Settings.
3. Note velocity - use the Note Velocity tab (if you're using Notation Composer) to see the Note velocities - just mouse-over the notes. If they are low (eg. 40 or lower), you can (1) click the Staff Select button (2) use Region/Convert Region to a selection of notes and (3) hold the L key (for "loudness") and press the Up arrow key to make the notes louder.
If the above suggestions don't help, please either post a copy of the file, or send me a copy at
support@notation.com and I will take a look at it.
ttfn,
Sherry