cant "find" dynamic controls in a PlaceHolder

hi asp.net newbie here again.. :) im having a problem with "finding" the controls i created dynamically in a placeholder. i want to find the textboxes i created to get the their value when i click a button. but when i run the program, Placeholder.Controls.Count = 0. but i can still see the textboxes in the webpage.. what am i doing wrong? >_< here's my code:

 protected void btnAddItem_Click(object sender, EventArgs e)
{
string TempNumOptions = txtNumOptions.Text;
int NumOptions = Convert.ToInt32(TempNumOptions);
Control c = new Control();
for (int i = 1; i < NumOptions; i++)
{
string OptionID = "NumOption" + i;
c = Pl ...