Cannot Update Database But There Were No Error!!

hai..i cannot solve this sproblem...i need to update my databse after i edited the textfield.then system will return me 'UPDATE SUCCESS'(because i return value UPDATE SUCCESS).this seem like nothing wrong.but when i check the database,data did not update!!have anybody know that?

thanks!!my coding as below,

#Region "Edit student Then save"


    Public Function editstudent(ByVal sIC As String, ByVal school As String, ByVal phone As String, ByVal pic As String, ByVal pwd As String, ByVal sname As String, ByVal gender As String, ByVal add As String, ByVal standard As String, ByVal osic As String) As String

        ' Create Instance of Connection and Command Object
        Dim myConnection As SqlConnection = New SqlConnection(ConfigurationSettings.AppSettings("ConnectionString"))

        Dim command As String
        Dim mycommand As SqlCommand

        command = "Update student_info set sic =@sic, Spassword =@pwd," & _
                  "sname =@sname, sphone=@phone,saddress=@add, sstandard=@standard,sschool=@school ,Sparent_IC=@pic ,sGender=@gender Where sic =@osic"

        mycommand = New SqlCommand(command, myConnection)
        mycommand.CommandType = CommandType.Text

        '' Add Parameters to Command
        Dim parameterIC As SqlParameter = New SqlParameter("@sic", SqlDbType.VarChar, 12)
        parameterIC .Value = sIC
        mycommand.Parameters.Add(parameterIC )


        Dim parameteroIC As SqlParameter = New SqlParameter("@osic", SqlDbType.VarChar, 12)
        parameteroIC .Value = osic
        mycommand.Parameters.Add(parameteroIC )

        Dim parameterpwd As SqlParameter = New SqlParameter("@pwd", SqlDbType.VarChar, 50)
        parameterpwd .Value = pwd
        mycommand.Parameters.Add(parameterpwd )

        Dim parametername As SqlParameter = New SqlParameter("@sname", SqlDbType.VarChar, 100)
        parametername .Value = sname
        mycommand.Parameters.Add(parametername )

        Dim parameteradd As SqlParameter = New SqlParameter("@add", SqlDbType.VarChar, 100)
        parameteradd .Value = add
        mycommand.Parameters.Add(parameteradd )

        Dim parameterphone As SqlParameter = New SqlParameter("@phone", SqlDbType.VarChar, 12)
        parameterphone.Value = phone
        mycommand.Parameters.Add(parameterphone)

        Dim parameterstandard As SqlParameter = New SqlParameter("@standard", SqlDbType.VarChar, 50)
        parameterstandard.Value = standard
        mycommand.Parameters.Add(parameterstandard)

        Dim parametersschool As SqlParameter = New SqlParameter("@school", SqlDbType.VarChar, 100)
        parametersschool.Value = school
        mycommand.Parameters.Add(parametersschool)

        Dim parameterpic As SqlParameter = New SqlParameter("@pic", SqlDbType.VarChar, 12)
        parameterpic.Value = pic
        mycommand.Parameters.Add(parameterpic)

        Dim parametergender As SqlParameter = New SqlParameter("@gender", SqlDbType.VarChar, 1)
        parametergender.Value = gender
        mycommand.Parameters.Add(parametergender)
        Try

            myConnection.Open()
            mycommand.ExecuteNonQuery()
            myConnection.Close()
            Return "Update Success !!!"

        Catch exc As Exception

            Return exc.ToString

        End Try

    End Function
#End Region


End Class