When adding data to a layer, you may get this error:
Quickmap: Unexpected Error Encountered
Object reference not set to an instance of an object..
This happens because the database that stores the layer is not compatible with the database drivers installed on your computer. This can happen if you install Microsoft Access, which may upgrade the drivers.
At the time of writing this, the only way to fix this is to send the database to Quickmap to have it upgraded so it works with your computer; however we are currently working on a feature in the next release of Quickmap (which will probably already be released by the time you are reading this) that allows you to upgrade your layer databases within Quickmap.
Addendum: It is currently our intention to replace this error with the option to fix (upgrade) the database, so if you are getting this error, it may be for a different problem and you should contact Quickmap in any case.