Resources.Load driving me a bit crazy

I'm working on Unity 3.3, and I have a text file in "/Assets/Resources/file.txt"

        TextAsset textAsset = (TextAsset) Resources.Load(file_path, typeof(TextAsset));
    if (textAsset == null) 
    {
        Debug.Log("STRINGTABLE: " + file_path + " file not found.");
        return;
    }

The 'file_path' var itself contains "file.txt" and this code snippet fails every single time. Every article or question that I've stumbled across via google basically says that as long as the file is in a directory named "Resources" then it will automatically be found and loaded, and apparently most people find that solution works for them, but it hasn't worked for me at all.

Is it something simple that I'm missing because I'm a beginner?

Remove the .txt extension from the string you're using (not the file)