Cannot get value of UpdatePanel element - asp.net

Question

I have a repeater inside an Update Panel. when I click the "Find Books" button repeater is modified according to the query.
What I want is to get the value of the DropDown when I click Add To Cart Button. But I can't get the value, instead the UpdatePanelAnimationExtender runs again. I added another button (TestingButton) inside the Update Panel. The UpdatePanelAnimationExtender runs when I click that button also.
My question is how can restrict the update panel only to the "Find Books" button? and how can I retrieve the value of DropDown outside the update panel? I added UpdateMode to conditional but it also not working.
aspx page
<p>Search by Author</p>
<asp:TextBox ID="txtAuthor" runat="server" Text="" AutoComplete="off" /><br />
<p>Search by Publisher</p>
<asp:TextBox ID="txtPublisher" runat="server" Text="" AutoComplete="off" /><br />
<asp:Button ID="btnFind" runat="server" Text="Find Books" OnClick="BtnFind_Click" />
<br />
<p>Search by Price</p>
<asp:RadioButtonList ID="RadioButtonList1" runat="server">
<asp:ListItem Text="Below Rs. 1000.00"></asp:ListItem>
<asp:ListItem Text="Between Rs. 1001 to 2500"></asp:ListItem>
<asp:ListItem Text="Above Rs. 2501.00"></asp:ListItem>
</asp:RadioButtonList>
<br />
<asp:TextBox ID="txtTest" runat="server"></asp:TextBox>
<asp:Button ID="Button2" runat="server" Text="Button"
onclick="Button1_Click" />
<asp:UpdatePanel ID="udpBooks" UpdateMode="Conditional" runat="server">
<ContentTemplate>
<asp:Button ID="btnTest" runat="server" Text="Testing Button" onclick="Button1_Click" />
<asp:Repeater ID="repBooks" runat="server" DataSourceID="SqlDataSource1"
onitemcommand="repBooks_ItemCommand">
<HeaderTemplate>
</HeaderTemplate>
<ItemTemplate>
<div id="bookBorder">
<table width="640px" height="70px" border="0">
<tr>
<td width="51%" style="padding-top: -20px">
<span class="title">Description:</span> :
<%# DataBinder.Eval(Container.DataItem, "description")%>
</td>
<td>
<asp:DropDownList ID="DropDownList2" CssClass="dropDown" runat="server" Width="100px">
<asp:ListItem>1</asp:ListItem>
<asp:ListItem>2</asp:ListItem>
<asp:ListItem>3</asp:ListItem>
</asp:DropDownList>
<br />
<asp:Button ID="btnAddToCart" CssClass="button" runat="server" Text="Add to Cart"
OnClick="BtnAddToCart_Click" />
</td>
</tr>
</table>
</div>
<br />
</ItemTemplate>
</asp:Repeater>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="btnFind" EventName="Click" />
</Triggers>
</asp:UpdatePanel>
<asp:UpdatePanelAnimationExtender ID="upae1" runat="server" TargetControlID="udpBooks">
<Animations>
<OnUpdating>
<Parallel Duration="0">
<EnableAction AnimationTarget="btnFind" Enabled="false" />
<FadeOut MinimumOpacity=".5" />
</Parallel>
</OnUpdating>
<OnUpdated>
<Parallel Duration="0">
<FadeIn MinimumOpacity=".8" />
<EnableAction AnimationTarget="btnFind" Enabled="true" />
</Parallel>
</OnUpdated>
</Animations>
</asp:UpdatePanelAnimationExtender>
Code Behind
public partial class Default3 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void SqldsOrderDetails_Selecting(object sender, SqlDataSourceSelectingEventArgs e)
{
string author = txtAuthor.Text;
string publisher = txtPublisher.Text;
string select = "";
if (author.Equals("") && publisher.Equals(""))
select = "select bookId, ISBN, Title, publisher, author, price, description from dbo.[book]";
else if(author.Equals("") && !publisher.Equals(""))
select = "select bookId, ISBN, Title, publisher, author, price, description from dbo.[book] where publisher=#publisher ";
else if(!author.Equals("") && publisher.Equals(""))
select = "select bookId, ISBN, Title, publisher, author, price, description from dbo.[book] where author=#author";
else if(!author.Equals("") && !publisher.Equals(""))
select = "select bookId, ISBN, Title, publisher, author, price, description from dbo.[book] where author=#author and publisher=#publisher";
SqlDataSource1.SelectCommand = select;
e.Command.Parameters.Add(new SqlParameter("#author", this.txtAuthor.Text));
e.Command.Parameters.Add(new SqlParameter("#publisher", this.txtPublisher.Text));
}
protected void BtnFind_Click(object sender, EventArgs e)
{
System.Threading.Thread.Sleep(2000);
// this.gvOrderDetails.DataBind();
this.repBooks.DataBind();
}
protected void ul_Click(object sender, EventArgs e)
{
Response.Redirect("default.aspx");
}
protected void BtnAddToCart_Click(object sender, EventArgs e)
{
txtTest.Text = "sd";
}
protected void Button1_Click(object sender, EventArgs e)
{
txtTest.Text = "sd";
}
protected void repBooks_ItemCommand(object source, RepeaterCommandEventArgs e)
{
DropDownList d = e.Item.FindControl("DropDownList2") as DropDownList;
txtTest.Text = d.SelectedValue;
Button b= e.Item.FindControl("btnAddToCart") as Button;
b.Text = d.SelectedValue;
}
}

Answer 1

For triggering
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
<ContentTemplate>
Some content that needs to be updated here...
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="FindBook" EventName="Click" />
</Triggers>
</asp:UpdatePanel>
as far as the value of DropDown into textbox is concern, you should place textbox in another updatepanel and set its value when user select a value from dropdown by calling update method.