@morrow without logs this will be hard to track down. can you ask your administrator to open up a support case for this?
This is a provider issue, probably caused by the proxying of the data by the telecom operator.
Many mobiles may show the ‘Bad request from mobile’ error when synchronizing their mobile with a server via z-push. This is not a problem with z-push or the mobile, but is caused by proxy-software run by your telecom operator.
Workaround: Due to the way that SSL works, you can setup your connection to use SSL, and your connection will not be proxied by your telecom operator. Set up your z-push server to accept SSL connections, and set your PDA to use the SSL-encrypted connection.