Xbee encryption not working?

I’m trying to set a encrypted communication between two xbees (series 1) but I’ve set the EE parameter to 1 (enabled) and I’ve set a key of 16 bytes (0123456789ABCDEF0123456789ABCDEF) to test it, but when I send a packet from one xbee to the other (in API mode) it has the same hexadecimal value (characters) than when it’s sent without encryption so it seems that it isn’t being encrypted.

If I disconnect the xbee from the XCTU and I reconnect it, the Key value is empty (i don’t know if its for security reasons or it’s not being saved).

How should I configure the devices to encrypt the communication?

Thanks

Yes it is working. You can verify this by turning off encryption on the receiving side. You see the encryption just encrypts the data for over the air communications. The receiving module then De-crypts the packet using its KY value.