How to use resume in this VBA macro

I created a macro for SUBSCRIPTING in text.

It subscript selectable text and increase font size by 0.35 %.

but when i use CALLOUT tool in corel draw,

After creating callout, write callout text and run this macro to subscripting selected text .

but it displays error message.

Please tell me how to fix it.

I write macro here to know what is it....

Sub SubScript()
    On Error GoTo Err_Handler
    ActiveDocument.BeginCommandGroup "subScrip"
    Dim p As Variant
    p = ActiveShape.Text.Selection.Size
    ActiveShape.Text.Selection.Position = cdrSubscriptFontPosition
    ActiveShape.Text.Selection.Size = p * 1.35

    Exit Sub

    MsgBox "An unexpected error has occurred", vbRetryCancel, "Please retry."
End Sub

Thanks in advance.......