Running A Userform To Update The Current Cell Value

I have to append the cell value with a user input string in to the same cell.
i.e, if the user types "Issue" in the cells ranging C1:C200, I would like to make a mandatory issue description to be entered by the user. So a user form with text box and command button was introduced which should append the cell value with the user input in the text box.

The issue that I have is with the cell selection within the code for the form.

ActiveCell.FormulaR1C1 = "Issue (" + TextBox1.Text + ")"

For example if the user tabs out from cell C3, the output from the userform will be written to D3 ? or if the user hits Enter key to come out, the output will be written to C4 and so on.
How can I make ure the output is going to the same cell?

Private Sub Worksheet_Change(ByVal Target As Range)
On Error Resume Next
If Application.Intersect(Target, Range("$C$1:$C$200")) = "Issue" Then

Dim MyForm As New UserForm1
MyForm.Show

Else

Exit Sub

End If

End Sub

'Code for the userform is below:

Private Sub CommandButton1_Click()
If TextBox1.Text = "" Then

' the user input is mandatory
MsgBox "Issue Details is mandatory", vbCritical, "Mandatory Field"
TextBox1.SetFocus

Else

' append the cell value with user input in the text box
'****issue is here in the next line
ActiveCell.FormulaR1C1 = "Issue (" + TextBox1.Text + ")"
Hide

End If
End Sub