PHP / MySQL update query problems

I'm having trouble making this query work:

if(isset($_POST['updateRecord'])) {
    mysql_query("UPDATE files SET title = '$_POST[title]', description = '$_POST[description]', internal = '$_POST[accessFile]', category = '$_POST[category]' WHERE title = '$_POST[title]'");
    header("Location: system-management.php?viewFiles=on");
}

It is definatly entering the if statement as the header is redirecting to the correct page. I have set the form submit to use the post method and even if I use the get method I can see that my form data is being passed.

I have tried quoting out the header location and error reporting (or die) on the query but it brings up no errors

The form submit button is within a table column as follows:

Is there something really obvious that I'm missing here?

Any help you can offer would be really appreciated!