D.Baba Fakruddin - do you have the same application at your side? or just wondering whether both of you are same 
what is not identifying as a 'Cell' It is identifying as a 'WebObject', as per swetha b its an webelemnt in her wetable?
I think the question is to get the row where there is Green in a certain time period.. so you just need to identify the column first depending on the time period, then in that column check the color of webelements in each row, if it matches with your criteria check the checkbox in that row of your webtable.
what is not identifying as a 'Cell' It is identifying as a 'WebObject', as per swetha b its an webelemnt in her wetable?
I think the question is to get the row where there is Green in a certain time period.. so you just need to identify the column first depending on the time period, then in that column check the color of webelements in each row, if it matches with your criteria check the checkbox in that row of your webtable.