sometimes I can't add contact account, my wallet version is 0.2.2, in Ubuntu, can somebody help?

for example:
localtest (unlocked) >>> wallet_add_contact_account  rewardsomebody BTSX6uPc7ZjkyKeHdkkr9wadzYktRn7KKixDbPo3UuDGYGtL1hcsFw
10 assert_exception: Assert Exception
!account_key.valid(): Provided key belongs to another account.
    {}
    th_a  wallet.cpp:1449 add_contact_account

    {"account_name":"rewardsomebody","key":"BTSX6uPc7ZjkyKeHdkkr9wadzYktRn7KKixDbPo3UuDGYGtL1hcsFw"}
    th_a  wallet.cpp:1462 add_contact_account

    {}
    th_a  common_api_client.cpp:899 wallet_add_contact_account

    {"command":"wallet_add_contact_account"}
    th_a  cli.cpp:540 execute_command
localtest (unlocked) >>>
localtest (unlocked) >>>
localtest (unlocked) >>> wallet_list_accounts
NAME (* delegate)                  KEY                                                             REGISTERED            FAVORITE       APPROVED       
hot105                             BTSX6Ep6HFeS67uzqrSZrzwyQpVudntuEG424RfWCv7x1zbjXg6Jb2          NO                    NO             0         
localremote                      BTSX5hzCPsQpBxd81SznNKMsVKzbd1i8YmyC6mVDFShJDLYC4bh5pA          NO                    NO             0         
localtest (unlocked) >>>

but when I use wallet_list_accounts, there is no account with the key "BTSX6uPc7ZjkyKeHdkkr9wadzYktRn7KKixDbPo3UuDGYGtL1hcsFw".