how do I play mpg4?

I'm assuming your using an SX line of servers.

Have you setup your devices? And created formats for them?

You'll get that error for a few reasons.

1) Your trying to play to many things off a video server, for example trying to play three videos at once off a 2 channel player

2) You don't have your formats / devices configured properly

Is this a new install. Can you get anything scheduled to play off the servers?

Have you looked at the SX setup guide? Setting up devices and formats is covered there.

http://www.trms.com.s3.amazonaws.com/...

There is also more in depth knowledge in the users manual.

http://www.trms.com.s3.amazonaws.com/...

Post any more questions if you need help.

-ray