Hi Roger,
i had to rebuild my server 2008R2 SP1 in german.
I ran through all .net updates first to get the latest 3.5.1 & 4.0 versions.
After that i ran through the webinstaller for 2.6.0, i also tried a download of the files and tried a manual installation with the same result.
I get the website showing up without any problem, but when i try to add an object nothing happens. I can select the picture, it started to be uploaded, i see it in the _Temp folder but when the upload process is finished i see ... nothing, no new added picture.
I set debug=true to eventually get an error, but nothing. I gave the IIS_USERS group full access to the gallery install folder underneath inetpub, but nothing.
I checked the mime type for silverlight, even it's iis 7.5 it might be possible it was missing, but it is there.
I thought it might be the german language, but since 2008r2 is only using UI language packs and the core is english i didn't expect a change, but i did install the english UI pack, and no change.
I created a video so you can exactly see whats going on, it's the same with ie8, ie9 and firefox. Also the application log is showing something baout .net, this might help for debug.
Let me know what you like me to gather as logs or what i can try.
Thanks
Andi