Application id missing in table HRP5133

hi all

i need a report to create a list of Application id (otype ND) from candidate id (otype NA) and Candidacy id (otype NE). i used table HRP5133 for this purpose. but while testing i am able to find that some of the records don't have any value in APPID field, can you please suggest why APPID is blank and a logic for getting applid from candidacy id or candidate id.

thanks

thomas..