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viewstate becomes null suddenly

Posted By:      Posted Date: December 04, 2010    Points: 0   Category :ASP.Net

in one aspx page, i load .ascx control dynamically,

in one conrol i have 3 gridviews, in which first displaying only one gridview, when i click on the particular field of gridview, second gridview displays and same as third,


second and third updatepanel and gridview is visible false by defaule and i make it visible from codebehind when user click on  as above

all gridview is in seperate update panel,

now in user click on any field , i store that field in viewstate, so when pageindex change of gridview, according to viewstate i fetch the data from database, and bind the gridview,

now when i change the pages of gridview, after moving throgh some pages,

suddenly viewstate becomes null,

and second and third gridview visible false and only one gridview (first one displays)

i can not find what is the problem, and how to solve it,

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