Please check,
ACS---> Network configuration----> NDG (where you have this switch) ----> Edit Properties----> Remove key.
NDG key overwrites aaa client key.
ACS provides the ability to define a key on a Network Device Group (NDG), as well as define a key on an individual NAS within that group. If the key is defined in both places, the NDG key takes precedence over the individual device key.
Regards,
~JG
Do rate if helps