Adding comments

I wanted to add a comment in reference to a DesktopX theme I downloaded today. On clicking the 'add comment' button a white box came up but I was not able to enter any text. I tried saving then clicking on edit without any success. Rather than leave an empty comment box with my name against it, I would like to successfully add my comments. Any thoughts or suggestions appreciated. I should add that I tried logging out and back in to no avail.