I follow tutorial from the macromedia help 'Developing a Web Application in Dreamweaver MX'. I use asp.net but when i want to view live data there are error like below.. why? but if i use the asp there are no error

Parser Error Message : File or assembly name System.Data, or one of its dependencies, was not found.

Line 1: <%@ Page Language="VB" ContentType="text/html" %>
Line 2: <%@ Register TagPrefix="MM" Namespace="DreamweaverCtrls" Assembly="DreamweaverCtrls,version=1.0.0.0,publicKeyToken=836f606ede05d46a,culture=neutral" %>
<b>Line 3: &lt;MMataSet
</b>Line 4: id="DataSet1"
Line 5: runat="Server"

Below is my computer specification :
Pentium III 733Mhz
Windows 2000 Professional
Macromedia MX
.NET Framework SDK Beta 2
IIS 5.0