Changing avatar and site logo

I have both the avatar plugin and the rebranding plugin installed. My problem is that everytime I try to change the login screen logo or the avatar it won't work.

For avatar: I tried the first option (upload) and I get a box asking me to select the part I want but I don't actually see an image. The option to use alternate upload gives me an error line: Error uploading file but then I see "avatar updated".

For the login logo (LOGIN IMAGE) - it just says error uploading file and goes back to the original screen. The image I am using is a jpg and the exact dimension requested.

Would these problems with the plugin or settings/permissions on my server?

Thanks!
Helen