$_FILES [var]['size'] returns 0 for small (30KB) file - why?

[Leslie WebsiteS]

I've got a php form handler which takes data from an html page and creates and sends an email with one or more attachments.
I wanted to be smart and make sure a file had a size GREATER THAN 0. So I set
$attachment1_si ze = $_FILES['attachment1']['size'];
if ($attachment1_s ize > 0) {
And my 30KB file size comes up 0.
And the error codes showed no error.
When I took out the test for size and assumed (oh, bad) the file had a size >0, the file attached to the email perfectly.
My question is this: why, for a SMALL file, am I getting a 0 size?
The php config upload_max_file size is 2M. The MAX_FILE_SIZE on the html form is 1000000.
Any suggestions? I'd really like to test the file size.

[dgreenhouse]

That's weird... Are you sure you're not making a mistake in the code somewhere? I'm sure you're actually uploading a "non zero" byte file.

Hmmmmm....

[Leslie WebsiteS]

Here's the relevant code

In trying to debug, I echoed the size to check - sure enough, it was zero.
When I commented out the line which tests the size (and its closing bracket), everything worked. So the actual size wasn't zero, even if that's what was in the variable.
Hmm...