The parameterized query which was not supplied

I keep getting this error :

The parameterized query '(@AdminEmail nvarchar(4000),@AdminPassword nvarchar(4000))SELECT' expects the parameter '@AdminEmail', which was not supplied.

Code:

Public Function AuthenticateAdmin() As Boolean
    Dim Success As Boolean

    Dim strConn As String
    strConn = ConfigurationManager.ConnectionStrings("HMVDb").ToString
    Dim conn As New SqlConnection(strConn.ToString())

    Dim cmd As New SqlCommand("SELECT * FROM Admin WHERE AdminEmail=@AdminEmail AND Adminpassword=@Adminpassword", conn)
    cmd.Parameters.AddWithValue("@AdminEmail", EMail)
    cmd.Parameters.AddWithValue("@AdminPassword", Password)

    Dim da As New SqlDataAdapter(cmd)

    Dim ds As New DataSet

    conn.Open()
    da.Fill(ds, "Admin")
    conn.Close()

    If ds.Tables("Admin").Rows.Count > 0 Then

        Dim aemail As String = ds.Tables("Admin").Rows(0).Item("AdminEmail")
        Dim apass As String = ds.Tables("Admin").Rows(0).Item("AdminPassw开发者_StackOverfloword")
        Dim aid As Integer = ds.Tables("Admin").Rows(0).Item("AdminID")
        Dim aname As String = ds.Tables("Admin").Rows(0).Item("AdminName")

        If EMail = aemail And Password = apass Then
            ID = aid ' Shopper ID that identify Ecader
            Name = aname
            Success = True 'Shopper is authenticated
        Else
            Success = False 'Authentication fail
        End If
    End If


    'Return the authentication result to calling program
    Return Success
End Function

Your @AdminEmail variable EMail is null. You cannot pass a null on a required parameter. Use DBNull.Value.

When using null, you are informing Sql Server that you are omitting the parameter. This can be useful for an optional parameter with a default value, but causes an error for a required parameter.

I recommend that you use always use a utility function when passing a value to a command parameter.

For example:

public static object GetDataValue(object value)
{
   if(value == null)
   {
       return DBNull.Value;
   }

   return value;
}

and then use

cmd.Parameters.AddWithValue("@AdminEmail", GetDataValue(EMail))

Is it possible that the EMail property is null (Email is Nothing)? I think you might get that error in that case. Be sure that EMail = String.Empty or EMail = "" before you set your parameter value.

Edit: Or as another answer suggests, you can send DBNull.Value instead if you actually want nulls in your database.

Step through your code and see what the value of Email and Password are. Chances are they are null.