package testproject;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.firefox.*;
Remove the dot at the beginning of your xpath expression. That way you have an xpath expression thaty could match everything. With the dot at the beginning you might retrict yourself depending on if the current node is the root node or not. Ther eis no way to know it. Just the fact the dot can only give you trouble. Unfortunately you cannot always trust what tools like firebug give you (it is still true in 99% of the case).
Of course, ensure that the elemetns you are targeting are already on the screen as suggested by the previous answer.