Question Message : "Some of your keywords may have been filtered by your settings." 

I cannot Find the monthly search volume of a keyword using Google Keyword Planner Tool, GKPT or GKT. I get the Some of your keywords may have been filtered by your settings, which explain that due to some of my settings some keywords may have been filtered in the search. However, I have checked with all my settings, there is nothing I have set that kind of setting. I want to able to search the particular search. I am not able to find the solution.

Possible Answer : 

When I was searching in google keyword planner tool or GKP, I noticed and made an observation that google omit some keyword, which are closely similar or even those who do not have enough volume, its is like google do not want us to know those keywords which have relatively low search volumes. 

It might look as google silent changes to its tool, which might affect some advertisers and well might make them re-think on their online marketing strageties.