My Itunes can't connect to Airport express

I'm using an Airport Express to play music from iTunes on to a speaker in another room from my iMac (late 2009. OS X Yosemite 10.10.3).

My Airplay button disappears intermittently from iTunes also which makes it hard, but even when its there the music only works occasionally.

Cheers.

Hey teampamps,

Thanks for the question. If I understand correctly, you are trying to play iTunes to an Airport Express and the Airplay icon doesn't appear. I would recommend that you read this article, it may be able to help the issue.

iTunes: Troubleshooting AirPlay and AirPlay Mirroring - Apple Support

Ensure that you followed these steps to use AirPlay in iTunes.

If the AirPlay icon still doesn't appear, try one of the following steps:

• If you want to AirPlay to an Apple TV, ensure that AirPlay is enabled on the Apple TV. From the Apple TV main menu, go to Settings > AirPlay. This should be set to On.
• If you want to AirPlay to an Airport Express, ensure that AirPlay is enabled in the device settings.
• If you want to AirPlay to a 3rd party AirPlay-enabled device, refer to the user guide.

Thanks for using Apple Support Communities.

Have a good one,

Mario