有关使用Visual_studio.net做网站的问题

[zzx_2004]

大家好！我是.net的初学者。最近使用Visual Studio.net做一个电子商务网站，调试过程中我遇到了一个问题，想了很久，上网查过，也找过相关的书看了，但还是解决不了。请各位帮我看看。
我创建了一个类叫Catalog，并声明为Pubic。代码如下：
Imports System.Data.SqlClient
Public Class Catalog
Public Shared Function GetDepartments() As SqlDataReader
' Create the connection object
Dim connection As New SqlConnection(connectionString)
' Create and initialize the command object
Dim command As New SqlCommand("GetDepartments", connection)
command.CommandType = Data.CommandType.StoredProcedure
' Open the connection
connection.Open()
' Return a SqlDataReader to the calling function
Return command.ExecuteReader(Data.CommandBehavior.CloseConnection)
End Function
Private Shared ReadOnly Property connectionString() As String
Get
Return System.Configuration.ConfigurationManager.AppSettings("ConnectionString")
End Get
End Property
End Class
之后的在一个Web控件中调用，代码如下：
Public Class DepartmentsList
Inherits System.Web.UI.UserControl
#Region " Web Form Designer Generated Code "
'This call is required by the Web Form Designer.
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
End Sub
Protected WithEvents list As System.Web.UI.WebControls.DataList
'NOTE: The following placeholder declaration is required by the Web Form Designer.
'Do not delete or move it.
Private designerPlaceholderDeclaration As System.Object
Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form Designer
'Do not modify it using the code editor.
InitializeComponent()
End Sub
#End Region
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
' The departmentIndex parameter is added to the query string when
' a department link is clicked. You need this because when the
' page is reloaded, the DataList forgets which link was clicked.
Dim listIndex As String = Request.QueryString("departmentIndex")
' If listIndex has a value, this tells you that the visitor
' has clicked a department, and you inform the DataList about that
' (so it can apply the correct template for the selected item)
If Not listIndex Is Nothing Then
list.SelectedIndex = CInt(listIndex)
End If
'Create a new Catalog object
Dim catalog As New Catalog()
' GetDepartments returns a SqlDataReader object that has
' two fields: DepartmentID and Name. These fields are read in
' the SelectedItemTemplate and ItemTemplate of the DataList
list.DataSource = Catalog.GetDepartments()
' Needed to bind the child controls (the HyperLink controls)
' to the data source
list.DataBind()
End Sub
End Class
说明：红色的是错误代码

运行错误有一个：
错误 1 未定义类型“Catalog”。 D:\MyCommerceSite\JokePoint\UserControls\DepartmentsList.ascx.vb 37 28 http://localhost/JokePoint/
给出的更正提示是：
1、检查类型定义和类型引用的拼写是否相同。

2、检查引用是否可以访问该类型定义。例如，如果类型在另一个模块中且已声明为 Private，则请将该类型定义移到引用模块中或将其声明为 Public。

3、如果类型已经定义，但定义它的对象库或类型库未在 Visual Basic 中注册，则请单击“项目”菜单上的“添加引用”，然后选择适当的对象库或类型库。

经过多遍检查，最后确认第3项最有可能，可是添加的组件那么多，我不知道要选哪一项，求各位老师指点。感激不尽！