these two form elements are out side of the form:
<input name="addblock" type="text" id="addblock" style="display:none" value="" />
<input name="seconddblock" id="seconddblock" type="text" style="display:none" value="" />
move them so they are after the form tag.
the attachment code looks correct, I dont see anything in the code that is preventing the attachments.
to debug, change the following line:
$GoToPage = "webcam_thankyou.php";
$GoToPage = "";
and add this code at line 1:
what size are the images you are uploading? try with very small images to see if that works, it may be that the image size is causing the upload to fail.