Hi rifayeem,
please not some of Drawbacks of your code.
1) "Eval" is misspelled as "eval"
2) tostring() in not a valid method its ToString()
3) double quotes arround Update is not true.
4) ">" sign after action="Update" is erronuous.
Note: C# is case sensitive so ToString cant be coded as tostring and Eval cant coded as eval.
However I have fixed all this as follow,
PostBackUrl='<%#"Payslip_Structure.aspx?action=Update&Empcode=" + Eval("empcode").ToString() + "&month=" + Eval("month").ToString() + "&year=" + Eval("year").ToString() + "&compname=" + Eval("compname").ToString() %>'
Thanks and regards,
Rk_Hirpara.