SQL server reporting; missing data in sub-reports when exported to EXCEL

i am having 2 independent reports which pulls data from sql database; when i run those reports independently, the reports shows data perfectly and i can export it to excel without any issue of missing/incorrect data in EXCEL. but when i tried to make either of the report; a sub-report of other report, then 开发者_开发技巧the data exported in excel is missing many rows in a table. I have confirmed the data is still there in table and its being pulled correctly, but i am unable to figure it out why it messes up data when i export it to excel when used as sub-report. any help in this matter is greatly appreciated