Error 4756 (Invalid stops) on SL modify

[Rafael Caetano Pinto]

I caught a 4756 error [Invalid stops], but I don't known that is happening here...

There is a buy position at 3284.000 with SL 3269.000. The current price is 3296.000. 

At this moment, I tried to set a new SL to 3284.020 and I got the error:

2017.01.16 16:17:00   CTrade::OrderSend: modify WDO$D (sl: 3284.020, tp: 0.000) [invalid stops]

Below there is the details of the situation. Someone can help me to find the problem?

Thanks by advance

[Trinh Dat]

SL must bigger Stop Level