Logo Setup doesn't work

[palle]

Installation went fine and i have no problems with running PLESK. Now i took a gif pic which i wanna use as logo. there appears just like a place holder for the logo at the upper left corner instead my logo. i already tried jpg and to resize and everything but it doesnt help. if i use the web browser from the webserver and use the localhost as address it works. i dont know what i could have done wrong. does anybody have an idea.