node.js - Firebase transaction not updating -

i'm trying increment counter value in firebase database using transactions. works first time, i.e. when value set 1, on updates after that, value isn't updating.

here's how code:

firebaseref.child("search_hashtags").child(hashtag).transaction(function(currentvalue) {     return (currentvalue || 0) + 1; }, function(error, committed, ss) {     console.log(error);     console.log(committed);     console.log(ss); }); 

the error log says "[error: set]"

i turned on firebase logging , i'm getting this:

p:0: server: {"r":3,"b":{"s":"ok","d":""}}   p:0: p response {"s":"ok","d":""}   p:0: handleservermessage d {"p":"search_hashtags/test","d":1}   p:0: server: {"r":4,"b":{"s":"ok","d":{}}}   p:0: listen response {"s":"ok","d":{}}   p:0: server: {"r":5,"b":{"s":"datastale","d":"transaction hash not match"}}   p:0: p response {"s":"datastale","d":"transaction hash not match"}   0: transaction put response {"path":"/search_hashtags/test","status":"datastale"}  

i'm doing similar transactions on other nodes in other parts of code , work fine, reason 1 fails...