Strange: SQL queries not functioning in my class

SOLVED
I had an obscure delete call that I was using for testing previously. Any inserts where being immediately removed from the database
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Well I have been coding a little system for myself, and for the most part it's been pretty straight forward without many problems. Recently, I came across a very strange problem that I cannot seem to resolve. I am hoping that someone else might see it and be able to figure out what is going on.

Basically, I have a 'modify' portion of my script. The admin (myself) logs in and can click a check box to add/remove this particular item from a category. I've monitored the POST variables and they are being passed when the form submits. I then strip these variables and pass them to an object that inserts (or removes) them from the appropriate table.

The problem is that they insert/remove queries for the categories is not working inside of the object (which I have called 'modify'). What is strange though, is that in this very same object I have an SQL query that updates some basic default info for the item . . . this query works, but nothing else will work.

Here is some of my code:

<?

class image
{
// Commented out some code
function modify($tour_id, $name, $default_image, $description, $keywords, $duration, $includes, $bring, $air)
{
    // update the default tour information (THIS WORKS)
    $sql = "update tours set name='$name', description='$description', includes='$includes', bring='$bring', keywords='$keywords' where id='$tour_id' limit 1";
    $sql = mysql_query($sql) or die(mysql_error());

	// Just testing . . . this doesn't work. In fact, it doesn't appear to do anthing at all
    $sql = mysql_query("select * from category_air");
    while($row = mysql_fetch_assoc($sql))
    {
        print_r($row);
    }
    
    // this also doesn't work. No errors are produced . . . nothing seems to happen
    $sql = mysql_query("insert into category_air values(`image_id`) values ('1')") or die(mysql_error());
}
}

PHP:

So to sum up: SQL insert works outside of the object. In the object only the first SQL query appears to run, no subsequent inserts or selects work. Any ideas?