use session

hi folks, actually i hv 2 dropdownlistboxes,based on the firstdropdownlist value,corresponding value will be binded to the second dropdownlist.i have done using javascript and xml.bt the problem is when i posted back to the server, i got the error says invalid callback/postback............ if i addded enableeventvalidation=false means i wont get any error bt not capturing the value.i donot know how to overcome this prob. plz help me out.

h.this is windows basd app. i have a one column and n rows in that database say column name is student id,row values are 1,2,3,4 ................n like that.in my frontend there is one textbox and one button.what i want is, when i hit the button,the textbox show 1 and again hiting button,textbox has to show 2,again iam hitting buton textbox has to show 3 and so on.....until my row value becomes null.how to do this.plz help me......

hi folks.i fetched the data from the database and bind it to the datagridview.what i want now is when i hit button i have to capture the coresponding row value seperately in a datagridview.how to get? for ex,datagridview has 5 rows and 5 column means when i hit the button, i should get the 5 row values seperately.iam in the urgent need of it.how to do this.am new to the winforms.am waiing for ur reply.