Vauxhall Zafira 09 key will not work central locking?

key fob will not activate central locking. button on dashboard operates central locking. when key is turned in drivers door lock only the drivers door locks. when the drivers door is opened, pinger activates as thought the key is still in the ignition or lights on. Have replaced battery in key and also tried the key in ignition, pressing lock and unlock on remote but no sound of anything happening. Have also tried the bluetak on the battery. Has anyone any suggestions.