I am having problems with my new Sony ericsson k850i!?

I bought my K850i last week and I found out that whenever people called or messaged me, my phone will only ring for about 10 seconds and stopped. This is very weird as my ringtone is about 20 seconds. Is there something wrong with the phone? Or I should do something to the settings?

sth wrong with the settings i guess.. gotta go change it somewhere.. try asking a shop for help.. =)