ASP Don't load page when click button?

I have a textbox and button to search information.
If I set the value of the textbox to "have", after clicking the button the button click event is accessed in the codebehind.
However, when I set value of textbox to "have box", clicking the button causes nothing to happen. I tried the alert function in pageload but it doesn't run.
How to fix the problem?
My code looks like:
... <asp:TextBox ID="TextBox1" runat="server" style="margin-left:200px;" Height="30px" Width="200px" BorderColor="#3399FF" BorderWidth="1px" Wrap="False"></asp:TextBox> <cc1:AutoCompleteExtender ID="AutoCompleteExtender1" runat="server" TargetControlID="TextBox1" ServicePath="AutoComplete1.asmx" ServiceMethod="GetCompletionList0" MinimumPrefixLength="1" EnableCaching="true"> </cc1:AutoCompleteExtender> <asp:Button ID="Button1" runat="server" Text="Search" style="margin-left:20px;" Height="30px"/ ...