http://forums.ulyaoth.asia/  by typing it in the web browser it works perfect,

But when I link to my forums from lets say a button like this:

<asp:Button ID="Button2" runat="server" Text="Go to Forums" 
            onclick="Button1_Click" PostBackUrl="http://forums.ulyaoth.asia/" 
            Font-Size="XX-Large" Height="71px" style="margin-left: 0px" 
            Width="235px" />

it will not work, it will not show my forums but a error instead of the correct forum page:

This is a error on the forum you can see it by using the button on www.ulyaoth.asia.

Do I just fail at making buttons or is there something else I do wrong here?

http://forums.ulyaoth.asia/forums/yaf_info.aspx?i=4 

I'm not sure, but I think it might have something to do with "PostBackUrl".