I have some problems changing the Global logo of our confluence environment.

Our company has a new name and a new logo and i tried to change it in the Administration Console of Confluence like i did it before with our old logo.
The logo didn't change and the old logo stayed in screen.
I tried changing it to default and that worked (it showed the atlassian logo) but after i did that the logo still didnt change, now i can't even change it back to the Old logo i used.
When i try and upload an image for a logo now i don't get an error but the picture is just not displaying. and the logo is still set to the Atlassian logo and also says that the current logo still is Default.

Another thing i noticed is that the image data is acting strange right now the image data says (after trying to upload the jpg) :

Image Data
H: -1
W: -1
JPEG

after a refresh of the page it says :

Image Data
H: -1
W: 0
?

and after another refresh it says :

Image Data
H: -1
W: -1
?

I didn't change any css things or edit the vm's
Hope you can help me with this problem

Regards,

Maarten van Wensveen