Bug while adding data to MS Access database in VB.NET 2010

I have a vb.net 2010 application that adds registries to a MS Access Patient db, but sometimes it does not add anything, until I reset the application (close and run it again) and that is very bad!

The table I want to add some information looks like this:

PatientId Proyect Email        RFC
-----------------------------------
1         firstP  [email protected]  KEY
2         secondP [email protected]   GTE
.... 

(Proyect is on purpose not project)

The structure of my table has an autoincrement ID value (PatientID): To know the next id I need to assign I have a function

Public Function GenerateAutoID()
        Return Me._patientDataTable.Rows(Me._patientDataTable.Rows.Count - 1)("PatientID").ToString()
    End Function

I am suspecting this is the bug that does not allow to sometimes insert new data to db... Then the function that executes when the save button is clicked is:

Public Sub Save()
        Dim query = String.Empty
        If Not _updateFlag Then
            ' save query
            query = "INSERT INTO Patient(Proyect,Email,RFC)"
            query &= " VALUES ('" & txtProyect.Text & "','" & txtEmail.Text & "','" & txtRFC.Text & "')"
            DatabaseFunctions.ExecuteQuery(query)
            MessageBox.Show("Data saved.", "System", MessageBoxButtons.OK, MessageBoxIcon.Information)

        Else
            ' update query
            '... code that updates
        End If
        Clear()
        Reload()
    End Sub

the codes includes Clear() that just resets all textfields in the form, Reload() and LoadDBData() :

Public Sub Reload()
        SetToolTipsToButtons() 'this is for some fancy buttons
        LoadDBData()
        txtPatientID.Text = (Integer.Parse(GenerateAutoID()) + 1).ToString()
        FillListNames()
        SetAutoComplete()
    End Sub



Public Sub LoadDBData()

    Dim query As String = "SELECT * FROM Patient "
    Me._patientDataTable = DatabaseFunctions.GetDataTable(query)
    dgvInfo.Rows.Clear()

    For Each dtRow In Me._patientDataTable.Rows

        dgvInfo.Rows.Add()
        dgvInfo.Rows(dgvInfo.RowCount - 1).Cells("colPatientID").Value = dtRow("PatientID").ToString()
        dgvInfo.Rows(dgvInfo.RowCount - 1).Cells("colProyect").Value = dtRow("Proyect").ToString()
        dgvInfo.Rows(dgvInfo.RowCount - 1).Cells("colEmail").Value = dtRow("Email").ToString()
        dgvInfo.Rows(dgvInfo.RowCount - 1).Cells("colRFC").Value = dtRow("RFC").ToString()

    Next    
    dgvInfo.ClearSelection()

End Sub

the class that deals with odbc connection is:

Imports System.Data.Odbc
Imports System


Public Class DatabaseFunctions

    Shared con As OdbcConnection
    Public Shared Sub CreateConnection()
        con = New OdbcConnection
        'con.ConnectionString = "Dsn=XXX"
        con.ConnectionString = "Dsn=XXX;uid=sa;pwd=XXXxxx;"
        con.Open()
    End Sub

    Private Shared Sub CheckConnection()
        If con Is Nothing OrElse con.State = ConnectionState.Closed Then
            CreateConnection()
        End If
    End Sub

    Public Shared Function GetDataReader(ByVal SQL As String) As OdbcDataReader
        CheckConnection()
        Dim cmd As New OdbcCommand(SQL, con)
        Dim dr As OdbcDataReader
        dr = cmd.ExecuteReader
        Return dr
    End Function

    Public Shared Function GetDataTable(ByVal SQL As String) As DataTable
        CheckConnection()
        Dim cmd As New OdbcCommand(SQL, con)
        Dim table As New DataTable
        Dim da As New OdbcDataAdapter(cmd)
        da.Fill(table)
        Return table
    End Function

    Public Shared Sub ExecuteQuery(ByVal SQL As String)
        CheckConnection()
        Dim cmd As New OdbcCommand(SQL, con)
        cmd.ExecuteNonQuery()
    End Sub
End Class

And the code when the form loads:

 Private Sub frmPatientRegistration_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Try
            Reload()
        Catch ex As Exception
            MessageBox.Show(ex.Message, "Systema", MessageBoxButtons.OK, MessageBoxIcon.Error)
        End Try
    End Sub

So I was thinking to change a little the save() code to know if the table has the same number of rowsm and if it has one more row everything is good, but if thats not the case try again....

I know this solution i was thinking of is not elegant, but maybe to avoid this the problem is in other part of the code... but I think it could be in the autoincrement, or something with the Access db file? Have you had any experience like this ??

I have debugged the program and it works fine, only when I run it as a standalone app sometimes it does not save anything.... until I rerun the program...