Diag Resp Time not displaying

Hi,

In st03 Diag Resp time is not showing daily at some particular time . In my system job is scheduled for every one hour but when i  log in to system (9:30 AM) then its not showing and  after sometime(10:30AM) its showing . This is not happening regularly . Actually I am new to basis and Your answer is very helpful to me.

Thanks,

suni.