The server tag is not well formed?

[hautt66]

I am getting the above error. I want to validate the textbox which allow some special characters but not letters and numbers. For that I wrote the below code but it is giving the above error.The code\[code\]<asp:TextBox ID="txtTag" runat="server" Width="250"></asp:TextBox>&nbsp;&nbsp;&nbsp;<asp:RegularExpressionValidator ID="reg1" runat="server" ControlToValidate="txtTag" ErrorMessage="*" Text="please check" ValidationExpression="/^[[\]'/\\@ &(){}+$%#=~"-`/*.&]([[\]'/\\@ &(){}+$%#=~"-`/*.&]*)$/" />\[/code\]What am I doing wrong?