Don, the instructions for the Pa900 say you need to do a Factory Restore of Global settings to complete the upgrade.

Sounds like an STS Mode setting. Check that out in the manual and experiment with different settings, but the light should be flashing so that it will allow the STS to change with the song. Sounds like your light is solid on.
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Graham, Korg Pa1000, Korg G1 Air, Countryman E6, Roland BA330, 2 x Roland CM-30, , Mackie SRM150