Cannot change User Manager Logo

Hello,

i’m trying to change the logo.

What i’ve done so far:
I have uploaded with ftp and placed my logo in a folder called umfiles (which i just created) and then pointed my usermanager logo config to /umfiles/mylogo.gif. It does not show my logo.

What am i doing wrong? is it possible to change the default logo in this version?

Device info:
Software version 6.46.2
Licence L5

Thank you in advance for any help!