Can you tell me why following code not working?

Imports System.Runtime.InteropServices

Public Class Form1

    'System time structure used to pass to P/Invoke...

    <structlayoutattribute(layoutkind.sequential)> _
    Private Structure SYSTEMTIME

        Public year As Short

        Public month As Short

        Public dayOfWeek As Short

        Public day As Short

        Public hour As Short

        Public minute As Short

        Public second As Short

        Public milliseconds As Short

    End Structure

    'P/Invoke dec for setting the system time...

    <dllimport("kernel32.dll")> _
    Private Shared Function SetLocalTime(ByRef time As SYSTEMTIME) As Boolean

    End Function

    Public Function SetDeviceTime(ByVal p_NewDate As Date)

        'Populate structure...

        'Substitute <your date="" object=""> with your date object returned via GPRS...

        Dim st As SYSTEMTIME

        st.year = p_NewDate.Year

        st.month = p_NewDate.Month

        st.dayOfWeek = p_NewDate.DayOfWeek

        st.day = p_NewDate.Day

        st.hour = p_NewDate.Hour

        st.minute = p_NewDate.Minute

        st.second = p_NewDate.Second

        st.milliseconds = p_NewDate.Millisecond

        'Set the new time...

        SetLocalTime(st)

        'Return SetLocalTime(st)

    End Function

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        SetDeviceTime("01/01/2010")

    End Sub

End Class