According to zee's code i did the following

Dim sPassword As String = FormsAuthentication.HashPasswordForStoringInConfigFile(pgen.fvar(Request, "ppass"), "md5")
Dim userID As Object = yaf.DB.user_login(1, pgen.fvar(Request, "puser"), sPassword)
Response.Write(userID.ToString)
If Not userID Is DBNull.Value Then
Dim idName As String = String.Format("{0};{1};{2}", userID, 1, pgen.fvar(Request, "puser"))

If (Request.QueryString("ReturnUrl") <> Nothing) Then
FormsAuthentication.RedirectFromLoginPage(idName, True)
Else
FormsAuthentication.SetAuthCookie(idName, True)
'yaf.Forum.
Response.Write("authen")
End If
Else
'AddLoadMessage(GetText("password_error"))
End If


i am gettin the error : System.ApplicationException: Failed to get configuration from Web.config. at yaf.Config.get_configSection() at yaf.YafDBConnManager.InitConnection() at yaf.DB.ExecuteScalar(SqlCommand cmd) at yaf.DB.user_login(Object boardID, Object name, Object password) at bestprax._default1.Page_Load(Object sender, EventArgs e) in C:\whb\Sites\9231\Web\default.aspx.vb:line 100

I also added the machine key in my web.config as well as yaf's web.config :
<machineKey validationKey="B01E4F14415E7E5930B41F69BDBCE9D7BDCF47A2AF163938C408DB2BDCD711D2BB734CE708F017E6F6FDC22E1488E245599EF1DFA2135848E7C39A3610FC555E" decryptionKey="BD120FA51B03C356CB262CDCF4E25D277E8070EE673916B3A77C83DDF3BE00CB" validation="SHA1" decryption="AES"/>

please help me out