VB.net: Can't run a public sub in another form - vb.net

Question

I have a Main (MDIParent) and Ticket (MDIChild). In Ticket form, there is a listview that displays the previous ticket trouble, pending and open ticket. When I add a new ticket trouble, there is a button BtnCreat_T, it will appear the TicketAdd form. The Ticket form will not close and I use the showdialog() for TicketAdd to show. When I add the new ticket trouble in TicketAdd form, the listview in Ticket form will not refresh, update, or reload.
Also, I noticed that in TicketAdd form I can't run the Public Sub ViewRecords created in Ticket form.
So here is my code in Ticket form Public Sub ViewRecords. I call this in Ticket form load:
Public Sub ViewRecords()
Dim i As Integer = 0
LvTicket.Items.Clear()
con.Open()
SQLString = String.Empty
SQLString = "SELECT * FROM TblTickets ORDER BY Ticket_ID DESC"
SQLDA = New SqlDataAdapter(SQLString, con)
Using SQLDT As New DataTable
SQLDA.Fill(SQLDT)
Do Until i = SQLDT.Rows.Count
With LvTicket
.Items.Add(SQLDT.Rows(i)("Ticket_ID"))
With .Items(.Items.Count - 1).SubItems
.Add(SQLDT.Rows(i)("Dept"))
.Add(SQLDT.Rows(i)("Aff_Per"))
.Add(SQLDT.Rows(i)("N_Prob"))
.Add(SQLDT.Rows(i)("Prob_Des"))
.Add(SQLDT.Rows(i)("DateTime"))
.Add(SQLDT.Rows(i)("Findings"))
.Add(SQLDT.Rows(i)("Status"))
End With
i += 1
End With
Loop
End Using
con.Close()
End Sub
And this is my code for adding the new trouble ticket in TicketAdd form BtnCreat_T button:
Private Sub BtnCreateT_Click(sender As Object, e As EventArgs) Handles BtnCreateT.Click
If CmbDept.Text = "" Or TxtAffectedP.Text = "" Or CmbNOProblem.Text = "" Or TxtProbD.Text = "" Or TxtFindings.Text = "" Or CmbStatus.Text = "" Then
MsgBox("Their is an empty field, please check!", MsgBoxStyle.Exclamation, "Ticket Details")
Else
If MsgBox("Are all fields are correct? Please double check!", MsgBoxStyle.Information + MsgBoxStyle.YesNo, "Ticket Details") = MsgBoxResult.Yes Then
GetTicket()
con.Open()
SQLString = String.Empty
SQLString = "INSERT INTO TblTickets (Ticket_ID, Dept, Aff_Per, N_Prob, Prob_Des, DateTime, Findings, Status)" &
"VALUES (#TID, #D, #AP, #NP, #PD, #DT, #F, #S)"
SQLCmd = New SqlCommand(SQLString, con)
SQLCmd.Parameters.AddWithValue("#TID", LblTicketID.Text)
SQLCmd.Parameters.AddWithValue("#D", CmbDept.Text)
SQLCmd.Parameters.AddWithValue("#AP", TxtAffectedP.Text)
SQLCmd.Parameters.AddWithValue("#NP", CmbNOProblem.Text)
SQLCmd.Parameters.AddWithValue("#PD", TxtProbD.Text)
SQLCmd.Parameters.AddWithValue("#DT", DTPicker.Value)
SQLCmd.Parameters.AddWithValue("#F", TxtFindings.Text)
SQLCmd.Parameters.AddWithValue("#S", CmbStatus.Text)
SQLCmd.ExecuteNonQuery()
MsgBox("Data has been saved! Your Ticket Number is: " & LblTicketID.Text, MsgBoxStyle.OkOnly, "Ticket Details")
con.Close()
EmptyField()
CmbDept.Select()
Ticket.ViewRecords()
Else
CmbDept.Select()
End If
End If
End Sub
After I click the BtnCreat_T button, the TicketAdd form will not close and the listview in Ticket form must be updated or refresh.
There is no error when running this code but I can't reload or update the listview in Ticket form.

Answer 1

As you mentioned you show the TicketAdd Form modal (.ShowDialog())
So I would suggest as long this TicketAdd from is showing, it's not realy relevant to update the Ticket form, because your application focus is clampt on your ticketAdd-Dialog.
After you close your TicketAdd form you can call ViewRecords from within the sub where you showed your TicketAdd form. There you have direct access to your true Instance of Ticketform (mentioned by #JayV)
But if you realy have to update every record as it gets saved you can handle it with an action you pass to your TicketAdd form
In your Ticketform where you show your TicketAdd, set the Action (Reference to the Sub Signature of Ticketform)
Dim lTicketAdd As New TicketAdd
lTicketAdd.SetUpdateData(AddressOf ViewRecords)
lTicketAdd.ShowDialog()
Extend your TicketAdd form with a Sub to asign the Action-Reference and where you save your DataRecord call this Action
'And Action to hold the Reference to your ViewRecords Code from the parent Form
Private _RefreshData As Action
'A sub to set this Action Reference
Public Sub SetUpdateData(ByVal vDelegation As Action)
_RefreshData = vDelegation
End Sub
Private Sub BtnCreateT_Click(sender As Object, e As EventArgs) Handles BtnCreateT.Click
.....
'Your code from above
'Instead of calling ViewRecord, call the Action
If _RefreshData IsNot Nothing Then
_RefreshData.Invoke()
End If
End Sub