Number of record varying from call to call

Hi ,

I have made call to Google analtics API and number of records i get on each call vary from time to time . Say in first call i get 800 records after some time i get 500 total records. I have not made any changes to parameters.Value each page is showing correct but count of some items are missing.

Am using example.report.php with my key and email .

Thanks
Jithin