Cannot add Products to a category

-- HikaShop version -- : 2.3.4
-- Joomla version -- : 3.3.6
-- PHP version -- : 5.4.19
-- Browser(s) name and version -- : Firefox 33.0
-- Error-message(debug-mod must be tuned on) -- : No error message. It just doesn't do the job!

I have been struggling to add a product to a category.
Basically I go the product.
Click Categories -> Add
Select the category I want to add it to.
Click OK
It shows a new screen I don't remember seeing before.
When I close it there is no change to my product category whatsoever.

I attach screen shots of the whole process.

In fact, I see this is happening with most things. I noticed it also when trying to add variants to a product too.
Also I am struggling to upload photos for the same reason.

Now I am venturing into the unknown....
I have attached a printscreen of what I think you want.

Hi Nicolas,
According to my friend this is more what you may be looking for:

Use of getAttributeNode() is deprecated. Use getAttribute() instead. mootools-core.js:108
TypeError: window.hikashop.ready is not a function index.php:911

Please can I get a response on this. What should I do? I cannot capture my shipment properly at the moment.

I suspect you have old version of media/com_hikashop/js/hikashop.js
Could you open this file and check the @version at the top?

* @version 2.2.1
I think

If I'm correct, you are using Hikashop 2.3.3, but js file is from Hikashop 2.2.1.
You can, update to Hikashop 2.3.4 ( don't forget to take a backup, just in case) and js file should be also updated.
Or extract media/com_hikashop/js/hikashop.js from Hikashop 2.3.3 installation package and upload it .

I checked out also other js files and it looks like you have mix of files from several versions.
You should update all js files from media/com_hikashop/js/ folder to the same version.

Thank you so much.
This has worked and solved our problem completely.