Fail to download through acsm file

Hi 

Recently, it failed to download the ebook after clicking the acsm file from Kobo.

The error mesaage is "digital edition fail to connect the delivery server, please confirm you link to the internet."

I am very sure I linked to the intenet and I also make a firewall exception of adobe digital edition.

The version of my adobe digital edition is 3.0 and the OS is windows xp 32bits.

Look forward for any reply.

Best regards,

CH