Enabling menu items on another form

[NOTSOSURE]

when i close a form i want to enable a menu item

i have attempted to do this with the code below, but each time i try and close the form i keep getting an error

"Object reference not set to an instance of an object"

can any one tell me where im going wrong?

    Private Sub frmEmployee_Closed(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Closed

        Dim frmMainMenuItem As frmMainMenu

        frmMainMenuItem.MenuItemEmployeeInfo.Enabled = True

    End Sub

here's my code when the user clicks the menu item on another form.

    Private Sub MenuItemEmployeeInfo_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MenuItemEmployeeInfo.Click

        Dim frmEmployeeOpen As New frmEmployee
        frmEmployeeOpen.Owner = Me
        frmEmployeeOpen.MdiParent = Me
        MenuItemEmployeeInfo.Enabled = False
        frmEmployeeOpen.Show()

    End Sub