Web Forms :: Used A Datalist Within Datalist?

i used a datalist within datalist i placed a panel and in the panel i placed a placeholder then a table in it .i placed the lables, textbox and checkboxes in the table from backcode that is in c# codei tried to find the control(Table) in datalist and also in placeholder but it shows null what is the reasonit gives the exception as in the subjectthe table name and reference names are same as i declared

Table tbl = (Table)pnlMentalStatusExam.FindControl("tbl");
Table tbl = (Table)phMentalStatusExam.FindControl("tbl");
tbl is same as i declared in the table creation

pls solve my problem

Table tbl = (Table)pnlMentalStatusExam.FindControl("tbl");
Table tbl = (Table)phMentalStatusExam.FindControl("tbl");