Security Code image not showing on site

I'm guessing you wore the wrong colored socks when you transferred the data (never, EVER, wear Orange socks while SCPing).

Maybe if you told which app is supposed to have the Captcha others will guess too.

I have run into a case in the past where the GD library did not provide a function that the CAPTCHA code (written in PHP) was expecting (don't know why). You may want to test out the functions your code uses to see if you can track it down to something specific. In my case I just commented out the offending function call making the trivially-easy CAPTCHA a tiny bit easier to break.