Alexa Rank is not updating daily?

thanks for the help

but its a strange case because my website was updating daily from 2.5 months and now its ranking is updating after 3 days, can something gone wrong with my website or is it normal ?

I know the question was not for me but let me give you an answer.
First of all, advertisers scan potential providers via alexa rank.
They spend lots of money just to get their hands on specific niche, alexa rank top 100K, top 10K etc lists.
Once your blog makes such a list you get real calls from advertisers.
Of course the next step is to prove the traffic is real but for that to happen you need to stand out via your alexa rank to even be considered in the 1st place.
Makes sense?
Now, many webmasters have nice traffic on their blogs but because most of their visitors are not SEO oriented and have no clue about alexa toolbar etc , their 2-5K/day traffic still does not necessarily translates in to low alexa rank.
So what webmaster are to do?
Inflate their alexa rank to match their real traffic or keep on sending their traffic stats all over the net in hopes someone will open their email.
From my own experience I know it does work either way but why not put your own alexa rank to work 24/7 ?
So in essence, webmasters do not need low alexa rank for higher traffic, they need low alexa rank to justify their already in place high traffic.
I personally , besides traffic/alexa rank I look at SERP's and PR
High ranking website with proven targeted traffic is where I want my banner to be at.