Clients not getting Combo updates from server

Question

I will try to explain the problem with my limited English knowledge.
My software update server works. The clients already update from it.
My server has downloaded and enabled the incremental AND combo 10.7.4 updates.
My clients have 10.7.3 and they can get the incremental update to 10.7.4.
When i choose to serve only the combo update from my server (by deselecting the incremental update) the clients think their software is up to date.
For some reason i am certain if my clients hade ≤10.7.2 OS everything would work fine.
Any solution?

Answer 1

I was able to solve it in the end. I had an ACL on Core Switch blocking traffic from AP to/fro WLAN/WLSM Switch. The initial traffic goes through the AP's and access switch (authentication and broadcast) to WLAN/WLSM switch through Core, thereby blocking layer 3 traffic and not layer 2 (authentication).
You might need to check your radio on your client (a = 5. Ghz or b/g = 2.4Ghz) to see that it corresponds to what is configured on the AP.