Also, what makes you think it didn't work? I did local transaction replacements on private testnets and it worked fine.
Would you be so kind to explain in short the simplest method to make transaction replacements for test? Just use createrawtransaction for 2 trxs with different nSequence? Sorry for dumb question, but I'm completelly new in bitcoin programming and it is very difficult to understand what to do exactly, too many new information.)