v1, "Missing or empty parameters:" when using `addOrder` about api HOT 2 OPEN

Similar issue here.
using in my API call:
values = json.dumps({'exchange_code': exchange[1]})
to get markets works perfectly, but:
values = json.dumps({ 'exchange_code': exchange[1], 'exchange_market': market[2], 'type': 'history' }).encode('utf-8')
to get market_data history returns:
{u'err_msg': u'Missing or empty parameters:', u'err_num': u'1057-14-01'}
but if I print values I get:
{"exchange_market": "XRP/USD", "type": "history", "exchange_code": "BITS"}
can someone help me here..
I also tried to remove the json.dumps() function with same result.
Thank you for your help.

NOTE: obviously that exchange and market variables return exch_name and mkt_name.

from api.

Solved it.
The problem was that I was creating a dictionary that didn't fit the required parameters, that hold the correct one dict. By expand this dictionary parameters fit.
Sorry for the inconvenience.

from api.