OTA/OMA sending issues

Hello.

I'm not sure to have subscribed the correct list.

I've a Kannel 1.4.3 installation working fine for SMS: I'm able to send text messages without any problem.

Now I tried to send OMA messages using sendota "script" to reconfigure APN setting on some mobile devices.
My Kannel is configured to connect via SMSC protocol (smsc = emi in kannel.conf) with my provider.

I post data to sendota but messages are not received. What my provider techical help-desk told me is that I'm using "UCP 51A MT4 string 
instead of UCP 52". I read the kannel docs and also ucp 52 specs from internet, but I'm not able to try where to check and what to change.

May someone help me?

thanks in advance to all
christian f.