How to lock an asset from further issuance?

I’ve created XBTC and would like to lock it such that no more XBTC can be issued. I used this command which has worked:

counterpartyd issuance --source 1LHpjmevxx3ZWydTL5PfoSiUiuYNbkqknm --quantity 21000000 --asset XBTC --divisible --description BTC

However, when I try and lock XBTC, I get the following error. How should I be specifying the command line?

counterpartyd issuance --source 1LHpjmevxx3ZWydTL5PfoSiUiuYNbkqknm --quantity 0 --asset XBTC --divisible --description BTC
Transaction (unsigned):
Confirm? (y/N) y
Traceback (most recent call last):
  File “/home/jeremy/counterpartyd_build/dist/counterpartyd/”, line 551, in
    print(unsigned_tx_hex) if args.unsigned else json_print(bitcoin.transmit(unsigned_tx_hex))
  File “/home/jeremy/counterpartyd_build/dist/counterpartyd/lib/”, line 404, in transmit
    return rpc(‘sendrawtransaction’, [signed_tx_hex])
  File “/home/jeremy/counterpartyd_build/dist/counterpartyd/lib/”, line 103, in rpc
    raise exceptions.BitcoindError(’{}’.format(response_json[‘error’]))
lib.exceptions.BitcoindError: {‘code’: -22, ‘message’: ‘TX rejected’}