Forms Data Controls :: PlaceHolder Contents Not Shown After PostBack

I have a GridView control which contains a custom <pagertemplate> with a <asp:PlaceHolder runat="server" ID="plcPages"> control. The .aspx.cs file contains the following code:
protected void Page_Load(object sender, EventArgs e) {
... {Other Code} ...
GridViewRow pagerRow = GridView1.BottomPagerRow;
PlaceHolder PagePlc = (PlaceHolder)pagerRow.Cells[0].FindControl("plcPages");
Button btnPage;
int iPageNum;
for (int i = 0; i < GridView1.PageCount; i++) { iPageNum = i + 1;
btnPage = new Button(); btnPage.ID = "btnPage" + iPageNum.ToString();
btnPage.CommandName = "Page"; btnPage.CommandArgument = iPageNum.ToString();
btnPage.Text = " " + iPageNum.ToString() + " ";
PagePlc.Controls.Add(btnPage); } }

Everything works fine the first time the page is displayed. But, when I click any pager button, including the Next and Prev command buttons that are not part of the PlaceHolder, the contents of the PlaceHolder are never re-displayed. I know from searching other posts that the PlaceHolder contents are lost during the trip to the server, but I am already recreating them every time the page is loaded. They are just never being shown again. I've spent the last two days playing with ViewState And every other combination.