Merging graphics from url

[catflap]

Hi



I'm trying to set up a merge field which will either:

1. Display a graphic retrieved from a url in a merge field if the url is OK.
2. Display some placeholder text if no url is in the merge field.
3. Display some placeholder text if the url text is present but no graphic can be downloaded - ie a bad url

I've managed #1 and #2, but #3 is causing me problems. This is what I have so far:



blank.jpg is just a blank graphic file I've made to act as a spacer.

'No image' text appears if the url text is blank.

But how can I check if the url text is present, but not correct?

If I run this as it stands I get a message appearing 'The linked image cannot be displayed. The file may have been moved.... (etc) - that's what I'm trying to avoid.

Thanks!