In case you've run into the problem of your pins not showing up on the map there are a couple things your can do to troubleshoot.
1. Set the appropriate z-level - many times your pins are displayed, but they're under the map. Virtual Earth will always assume the zero z-level, so ensure that you've distinctly set a z-level that's not zero.
2. Refresh the data - there's an undocumented way to refresh the data over the map. Simple call map.m_vegraphicsmanager.Update(); to refresh your pins, lines or polygons over the map.
3. Raise the dpi - Virtual Earth will not render pins that are less than 96 dpi; so, if you're trying to render pins that are 72 dots per inch you're going to need to raise it.