Photo uploading

Can anyone answer this question:

I have previously uploaded jpg photos without problems. Coming back to the site I find that 'photo' upload has now become a 'post' and although I point to a photo on my computer the software does not recognise any file and leaves a 'greyed' out area. I can't find an info or FYI section on this site. I have always found this site and the entire RSPB site a difficult one to navigate.

 

Anyone any ideas/ explanations??