When I setup my Joomla website I installed RS2 gallery and tested it by uploading a few images and it worked fine

Now I have made a few websites and they are live but the users are not able to upload images. When I tested and installed this it was done across a network

Users can create albums but when they put in the details to upload a picture and click the upload button nothing happens. There is no audible sound either. On the bottom righthand side of the web browser there is an message that says error on page.

the error read
line 534
Char 4
Error \'1_cat.value\'is null or not an object

Has anyone seen this or know how to resolve it

Thanks