Some Branch of my plant are dying.

There are two possibilities. The first, which is also the most likely, is that it is a root rot, perhaps caused by too much water or parasites in the soil. The second is that a borer larva ate the trunk. If you see sawdust coming out of a hole in the trunk, it is borer, otherwise a radical problem .. In any case, cut away the rotten branch to the healthy part, and disinfect the cut with plant putty.