This things happens many times.There are a lot of my keywords is in first position in Google.com. But not getting traffic. I checked keyword tool and saw that there are huge traffic for this keyword. So, I think keyword tool only gives us an idea about traffic but not exact.
I would still recommend you to check your CTR stats for this keyword in Google Webmaster Tools. I wrote a post in my blog to illustrate my point: Why High Search Engine Ranking Is Not Enough
Maybe you are targeting the wrong keyword. It's useless to rank in Google if no one is searching so you have to be careful in choosing it... You need to use the keyword tool in choosing the right keywords.
Use any other tool to search monthly traffic, this keyword must have traffic and even on 5th place your site must get some reason able traffic.
If you're going to target such low competition keywords it's pretty much vital to be #1. Otherwise you'll see very little traffic.
same problem is happening with me. one of my site is on 6th position but still not getting more than 3-4 visitors per day. even keyword traffic is more than 50k. i am trying to build more backlinks..
you have only 1,9K searches in a month. your website is only 4th for this search term. this explains everything. to get traffic from that keyword you need to be 1st on that keyword
low volume, first and second place will eat up all of that traffic, max 40 uniques a day in 1st place worldwide, if they offer good services then forget about getting any traffic. US traffic is probably half that so I would look at all the long tail words and try and create as much content around them as possible, you will get much better esults that way.
Highly surprising. But whether no.3,2,1 have sufficient traffic. Check it.and find out where from there is traffic. It may help you to amend yourself.
Getting on PR 4 isn't a easy task at all. Maybe your keyword having low searchers. Start keyword research again and target on new one. Besides continue quality link building with relevant sites. Relevant niche can only give you targeted traffic for this rare keyword.