PHP Upload Script Not Working

My PHP upload script is not getting anything from my form. Here is my form:

<small>Must be JPG, max 200kb</small>
<input id="image" type="checkbox" name="image" value="yes">
<input type="file" name="file" id="file">

Here is the section of PHP that handles the upload, I know that $image does infact = 'yes', so it looks like the problem is with the $_FILES array, as $_FILES["file"]["size"] is empty:

if ($image=="yes" && $_FILES["file"]["size"]>0) {
    if ((($_FILES["file"]["type"] == "image/jpeg")
        || ($_FILES["file"]["type"] == "image/pjpeg"))
        && ($_FILES["file"]["size"] < 200000))
          {
          if ($_FILES["file"]["error"] > 0)
            {
            $picstuff="Return Code: " . $_FILES["file"]["error"] . "<br />";
            }
          else
            {
            $picstuff= "Upload: " . $_FILES["file"]["name"] . "<br />
            Type: " . $_FILES["file"]["type"] . "<br />
            Size: " . ($_FILES["file"]["size"] / 1024) . " Kb<br /><br><br>
            <center>Please note it can take a couple of minutes for the image to be processed.</center><br><br>";

            move_uploaded_file($_FILES["file"]["tmp_name"], "images/$id.jpg");
            $query="UPDATE content SET image='yes' WHERE `id`='$id'";
            $result=mysql_query($query);
            }
          }
        else
          {
            $picstuff = "Image too large or incorrect format. Please upload a jpeg less than 200kb.";
            $image= "no";
            $query="UPDATE content SET image='No' WHERE `id`='$id'";
            $result=mysql_query($query);
          }
    } else
          {
            $picstuff = 'No File found';
            $image= "no";
            $query="UPDATE content SET image='No' WHERE `id`='$id'";
            $result=mysql_query($query);
          };

Every time I try upload I just get the 'No File found'. Would appreciate any help!