create controls dynamically in master's child pages in C#?

Question

I have creating controls dynamically successfully but when i applied master page then throwing an error "Object reference not set to an instance of an object." below is the my code.

 

protected void GenerateTableOnDelete(int rowsCount, int deleteID) 

{             

rowsCount--; 

Table table = new Table();             

table.ID = "Table1"; 

PlaceHolder1.Controls.Add(table); 

const int colsCount = 6; 

TableHeaderRow header = new TableHeaderRow(); 

TableHeaderCell headerTableCell1 = new TableHeaderCell();             

headerTableCell1.Text = "Item Name";            

 header.Cells.Add(headerTableCell1);                             

table.Rows.Add(header); 

for (int i = 0, k = 0; i < rowsCount; i++) 

{ 

if (i < deleteID)                    

 k = i; else                    

 k = i - 1; 

if (deleteID != i) 

{ 

TableRow row = new TableRow();                    

 row.ID = "Row_" + k; 

for (int j = 0; j < colsCount; j++)

 { 

if (j == colsCount - 6) 

{ 

TableCell cell = new TableCell(); 

DropDownList ddl = new DropDownList();                                                        

ds = fetchStates();                            

 ddl.DataSource = ds.Tables[0];                            

 ddl.DataValueField = "EmpId";                            

 ddl.DataTextField = "EmpName";                             

ddl.DataBind();                            

 ddl.ID = "DropDownListRow_" + k + "Col_" + j;                             

cell.Controls.Add(ddl);                             

row.Cells.Add(cell); 

} }                     

table.Rows.Add(row); 

} } 

SetPreviousDataOnDelete(rowsCount, colsCount, deleteID); 

ViewState["RowsCount"] = rowsCount; 

}

 at this line getting error Line 49: Table table = (Table)this.Page.FindControl("PlaceHolder1").FindControl("Table1"); // **** if (table != null) {

 

private void SetPreviousData(int rowsCount, int colsCount) 

{ 

Table table = (Table)this.Page.FindControl("ContentPlaceHolder1").FindControl("Table1");

for (int i = 0; i < rowsCount; i++) 

{ 

for (int j = 0; j < colsCount; j++) 

{ 

if (j == colsCount - 6) 

{ 

 DropDownList ddl = (DropDownList)table.Rows[i+1].Cells[j].FindControl("DropDownListRow_" + i + "Col_" + j); 

 ddl.Text = Request.Form["DropDownListRow_" + i + "Col_" + j];

 } } } }