Search and Replace Problem

[FrozenInferno]

I have an ebook with spaces between paragraphs that I would like to remove. I went under the search and replace tab and saw that there were <br/> tags after every paragraph. So I typed </p><br/> in the first box and just </p> for the replacement text, but it doesn't seem to to anything, and the <br/> tags still remain. What am I doing wrong?

Edit: I figured out the problem. I had already converted the book beforehand and Calibre seems to save a previous copy of the file, and any conversions done subsequently are applied to the original. So I disabled Calibre from automatically backing up the original file in the Tweaks section of the Preferences.