TextBox again. I have no way out!!!

[FatBear]

Dear friends,
I have a problem that I don't know how to solve it. I want to load a text file's content (just one line) in to a textbox. I tried to do it many times with many ways, but I failed. This is my code:

Dim readFile As New StreamReader(variable.dataPath & "\" & variable.monthView & variable.yearView & variable.MST & variable.Loai & variable.Method & ".txt")
 
 Dim temp As String
        Try
            temp = readFile.ReadLine
            RefFrm.frmDoanhThuVATTNDN.txtDT11.Text = temp
        Catch ex As Exception
            MessageBox.Show(ex.Message, "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1)
        End Try
 
        readFile.Close()

'this is a class, to make form DoanhThuVATTNDN globally
Private Shared p_frmDoanhThuVATTNDN As frmDoanhThuVATTNDN
Public Shared Property frmDoanhThuVATTNDN() As frmDoanhThuVATTNDN
        Get
            Return p_frmDoanhThuVATTNDN
        End Get
 
        Set(ByVal Value As frmDoanhThuVATTNDN)
            p_frmDoanhThuVATTNDN = Value
        End Set
 
    End Property

Or

Dim readFile As New StreamReader(variable.dataPath & "\" & variable.monthView & variable.yearView & variable.MST & variable.Loai & variable.Method & ".txt")
 
 Dim temp As String
dim form as new frmDoanhThuVATTNDN
        Try
            temp = readFile.ReadLine
            form.txtDT11.Text = temp
        Catch ex As Exception
            MessageBox.Show(ex.Message, "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1)
        End Try
 
        readFile.Close()

Although it could load textfile content into the variable "temp" but I did not load into texbox.