when using localization with resources all you need is to set the variable
title to that string
like
Text="<%$ Resources:Resource, EditBtnText %>"

where Resource is the file Name and EditBtnText the String inside that
Resource file

if you are using

AutoGenerateEditButton="True"

you need to delete this and creat an Button
like
<asp:ButtonField ButtonType="Link" Text="<%$ Resources:Resource, EditBtnText
%>" CommandName="Edit" />

to know further about Localization, please take a look at this Video:
http://www.asp.net/learn/videos/view.aspx?tabid=63&id=40