I use ListPicker from Silverlight Toolkit for WP August 2011 as below but it doesn't work
<controls:PanoramaItem Header="settings">
<toolkit:ListPicker>
<toolkit:ListPickerItem Content="5" />
<toolkit:ListPickerItem Content="10" />
<toolkit:ListPickerItem Content="15" />
<toolkit:ListPickerItem Content="20" />
<toolkit:ListPickerItem Content="25" />
<toolkit:ListPickerItem Content="30" />
</toolkit:ListPicker>
</controls:PanoramaItem>
Tried to replace by ListPicker from Silverlight Toolkit for WP February 2011 but it has same problem.
But I can use ListPicker from Silverlight Toolkit for WP February 2011 on an app which used SDK v7.0. Seems the problem causes by SDK v7.1
Found the reason! It's because ListPicker only can contain 5 or less than 5 items. If the list contains more than 5 items, using ListBox instead.