Unable to modify CO

When is send a CO , and try to modify the SL , it doesn't seem to modify the trigger price . Sending the snippet for reference
order placement -
access_token = kite.set_access_token(data["access_token"]) # add this before ordering,

order_id = kite.order_place(exchange = "NSE", tradingsymbol = "SBIN", transaction_type = "BUY", quantity = 1, order_type = "MARKET",validity = "DAY", trigger_price = 302.00, product = "MIS", variety='co')

The order and the SL order is placed successfully.

Modify Order

print " sending modify order"
access_token = kite.set_access_token(data["access_token"]) # add this before ordering

modified_stop_loss = kite.order_modify(order_id=sl_id, parent_order_id = primary_id , exchange="NSE", tradingsymbol="SBIN",trigger_price= 304.00,product = "co", variety='co')
print " Modify Order complete", modified_stop_loss

Result - it does not modify the trigger price. although returns the same SL id successfully.
Result says it modified but it does not reflect in the order book.

**************************************************************
SL ID: 170809000450265

sending modify order
Modify Order complete 170809000450265