jip i did.. but maybe im not putting it in the right place?

i got this code and it works
================================================== ===
Option Explicit
Private Sub CommandButton1_Click()
Dim myStr As String
Dim iCtr As Long
Dim mySep As String

mySep = ", "
myStr = ""
With Me.ListBox1
For iCtr = 0 To .ListCount - 1
If .Selected(iCtr) = True Then
myStr = myStr & ", " & .List(iCtr)
End If
Next iCtr
End With

If myStr = "" Then
'nothing checked
Else
myStr = Mid(myStr, Len(mySep) + 1)
End If

Worksheets("inv 1st page").Range("d42").Value = myStr
Unload UserForm1
Sheets("DATA SHEET").Select
Range("A111").Select

End Sub

Private Sub UserForm_Initialize()
Dim myRng As Range
With Worksheets("inputpage")
Set myRng = .Range("c1", .Cells(.Rows.Count, "c").End(xlUp))
End With

With Me.ListBox1
.MultiSelect = fmMultiSelectMulti
.ListStyle = fmListStyleOption
.List = myRng.Value
End With
End Sub

================================================== ===

now i want to add this and get the message popup that say

unable to get the activate property of the range class
================================================== ===

Private Sub CommandButton1_Click()
Dim i As String
Dim Lrow As Variant
Lrow = Sheets("Sheet1").Range("C65536").End(xlUp).Offset( 1,
0).Activate
If TextBox1.Value < "" Then
ActiveCell.Value = TextBox1.Value
End If
CommandButton1.Enabled = False