Resolved. You have to check whether the shape is an OLE control:
Code:
For Each oTB In ActivePresentation.Slides(1).Shapes
If oTB.Type = msoOLEControlObject Then
If oTB.OLEFormat.Object.Name = c Then
oTB.OLEFormat.Object.Text = TaskStatus
If TaskStatus = "B" Then oTB.OLEFormat.Object.BackColor = RGB(0, 0, 255)
If TaskStatus = "R" Then oTB.OLEFormat.Object.BackColor = RGB(255, 0, 0)
If TaskStatus = "A" Then oTB.OLEFormat.Object.BackColor = RGB(255, 204, 0)
If TaskStatus = "G" Then oTB.OLEFormat.Object.BackColor = RGB(0, 255, 0)
Exit For
End If
End If
Next oTB