title: ASP.net textbox Validation issue
body: <p>i have a regular expression on ASP.net textbox control that validate for user input it should be only letters and numbers within  6 to 200 character 
  this is my code </p>
  
  <pre><code>&lt;asp:TextBox ID="txtCategory_description" runat="server" Style="width: 485px;" Height="70px"
                                                              TextMode="MultiLine"&gt;&lt;/asp:TextBox&gt;
                                                      &lt;asp:RegularExpressionValidator ID="RegularExpressionValidator2" runat="server" ErrorMessage="Invalid Category name"
                                                              ValidationExpression="^[a-zA-Z0-9._-]{6,200}$" ControlToValidate="txtCategory_description"
                                                              Display="None"&gt;&lt;/asp:RegularExpressionValidator&gt;
  </code></pre>
  
  <p>the problem is where i wrote in the textbox any HTML code like  it accept it and send me to error page of 
  can any one help me ??</p>
  
  <p>note : on my page i have another regular expressions if i left all of them wrong , that regular expression also work well , the problem appear if it is only the wrong one </p>