incr not working properly in redis + node.js

i have one set named "UserActivity:[id]

when i am updating it within script using node.js it is not incremented. below is the my code.

    // redisCli.incr("UserActivity:" + Id, function (err, Ctr) {
    redisCli.incrby("UserActivity:" + Id, 1, function (err, Ctr) {
        console.log(Ctr);  //this is always return "1" 
        //when i have checked it using redis-cli.exe 
        //get "UserActivity:Id  -> "1"
    });

    //in above case id value is 1 

why???? if i am updating it with redis-cli.exe it works perfect !!!! (and it is showing result as 1)

i think it was some datatype issue, because within code it is return value as string, but using redis-cli.exe it is return integer.

please help me