Topic: Only part of the image is uploading

I am using plupload with flash runtime so that users can upload images to a website.

It is working on my local version of the website, but when I use it on the remote (shared host) version, instead of the success green tick, it shows a yellow !. 

This process only takes about 5 seconds.

When i check the file in the browser I see that about 1/4 of the image is there. That is, I can see the top quater of the correctly resized image, but the bottom 3/4 is just grey.

So it starts to upload and then stops.

Can anybody tell me a possible reason for this? thanks.