Robert, I changed the code as you suggested.
<mx:Label click="navigateToURL(new URLRequest('{data.Photos}'), '_blank');" htmlText="Abbreviation: {data.Photos}"/> (only removed the <u> tag because I was getting an error)
With the last line changed like that, the link is now clickable but it leads to ...Flex project folder.../bin-debug/%7Bdata.Photos%7D. When I cnahge " URLRequest('{data.Photos}') " to a HTML link to the pictures directory or one of the pictures it opens the address. I guess the problem is that when it's done this way it is not reading from the field in the layer of the service.
htmlText="Abbreviation: {data.Photos}" is leading to the right address because it's getting its data from the layer in the REST service but the other {data.Photos} is recognized just as a text for a link I guess.
Sorry for my English but I'm trying to explain it with as much detail as I can.
Thanks for the replies!
Deyan Kiryazov