Airport Util. will see Express Stations on one computer but not the other...vexing!

[icibaqu]

I have 2 airpot express stations set up as clients for iTunes streaming. Streaming works from iPhones, iPad, Macbook Air (High Sierra), but NOT from iMac (Early 09, El Capitan 10.11.6). When I open airport utility from the laptop, i see all express base stations connected to the network. When I do the same on the iMac, I do not.
Unfortunately the iTunes library is on the iMac. I "believe" that around the time I updated to iTunes 12.6.3 i lost the ability to Airplay from this computer only. (worked on macbook air, for instance). No matter what I do, I do not get the airplay icon back in iTunes. I have all connected to the same wifi network. I even factory restored the airport express stations in case that was the issue. it wasn't.
Can anyone offer some assistance. I'd really like to be able to stream my iTunes library again.

 

[icibaqu]

so almost 100 views and no one has an idea of how to solve this?

 

[icibaqu]

For other reasons, and in part for this one (and b/c I couldn't delete iTunes, etc.), I completed a clean install of El Capitan on my iMac.

Issue resolved.