If there is a version mismatch between the VX and APs, any config changes on the VX will not be propagated to the APs. First thing to do is run the command #show adoption status.
in the CFG-STAT column you will find the AP status, what does it say?
If it says version-mismatch go ahead and upgrade per Roberts instructions above:
Note that the VX9000 should include all APs upgrade versions but those are probably LEAN images so even if you upgrade the APs you will not have GUI access to them and will get the 404 error. You should however be able to SSH into them at the very least.
Christoph S.