I got a very simple user control (visifire charts + datepickers and some radiobuttons to control filtering etc):

```
<GroupBox Header="Scale" Width="159" HorizontalAlignment="Left" Margin="10,47,0,0"
          Height="38" VerticalAlignment="Top" Name="scalingBox">
    <Canvas Height="16">
        <RadioButton Name="scaleDays" Content="Days" GroupName="g2" Width="47"
                     IsChecked="True" Checked="scale_Change"/>
        <RadioButton Name="scaleHours" Content="Hours" GroupName="g2" Canvas.Left="60"
                     Width="59" Checked="scale_Change"/>
    </Canvas>
</GroupBox>

```

First bit is that setting `IsChecked` to true on the first button doesn't do anything when the control is displayed. 

Searching for a workaround I exposed some public methods to check the buttons I want from the parent window, but when I have more than one `MyControl` calling these methods only checks the buttons on one instance where the methods was last called. like this:

```
myControl1.SetDefaultScale();
myControl2.SetDefaultScale();

```

only checks the buttons on `myControl2`, leaving all the buttons in the group unchecked on `myControl1`.

Any ideas what may be causing this?

---

And yes, it was the group name that got shared among all the controls... Thanks Aran