Couldn't use preparelockunspentfrom with external privatekey when exchange? [closed]

+2 votes
Hi, I have a problem with API preparelockunspentfrom when i perform exchange?

preparelockunspentfrom 16UyRXhgeyBrNzzAL5QAkGqWdxTHpCJ3TKycan '{"goattoken":100}'


error code: -709
error message:
Private key for from-address is not found in this wallet


 I research and found some solutions for this problem, as:

But after trying, I receive new problem when i call createrawexchange API with txid is result of sendrawtransaction.
error code: -4
error message:
Signing transaction failed


Please help me.
asked Aug 31, 2017 by ThanhPT
closed Sep 1, 2017 by MultiChain