why my core dump file is "? " in main process in solaris 10

why my core dump file is "? ?" in main process in solaris 10?

and called funtion is ok , can see the name and address!

this problem is only occurent in solaris 10, not in solaris 8

for exampel, pstacking core file is :

?(0x0034x,......)-this function in main process

ACE_Rector::svc()(0xff3e........)this is called function

[360 byte] By [npuyuntian] at [2007-11-26 11:43:38]