Aastra failed upgrade to 1.4

Hello folks!
I’ve bought a 480i CT and i would want to upgrade the firmware, but
i’ve got a problem.
I’m using a windows based tftpd server, that i use with success for the
upgrade of Grandstream GXP2000.
When i do the upgrade from webpage of Aastra, i get a page "Invalid
download settings…"
What does it mean?
I’m putting only the ip of tftp server and the file’s name…
And also with TFTP via a windows’ server the download goes in time out…I’ve setted an higher timeout, but it fails anytime…
Do you know a tftp server that works well?
Many thanks!

try using FireFox instead of IE … usually works for me.