concatenate problem

[s-michael@xxxxx (Michał)]

Hi,

I wanted concatenate: "sip:"user"@"domain,where domain is char * passed to the function but my program exits on the first pj_strcat2. I can't find why.
this is part of my function: 

SinReg(char *sipserv)
{
....
pj_str_t output = pj_str("");
pj_strcat2(&output,"sip:"); //here program exits
pj_strcat2(&output,"user");
pj_strcat2(&output,"@");
pj_strcat(&output,&pj_str(sipserv));

...
}

Thanks for any help
Michael