In ColumbusPlus the Remote Reference is a requirement for the Cluster system to access a measurement's corresponding images and perform a batch analysis. You will find Remote Reference under the Measurement Info tab in the Browse view. If the Remote Reference is missing a Cluster analysis will fail. Essentially it is a URL being the path to the images on the shared file system.
There are a number of reasons why the Remote Reference might be missing, these include:
Data imported before the Cluster was available. This can be made good and is covered here:
http://forums.cambridgesoft.com/messageview.aspx?catid=65&threadid=3767&enterthread=y
Data import repeated as a result of missing data. For example data imported was started but stopped before completion. The import was then repeated to patch in missing data however the Remote Reference is missing. This behaviour is improved in Columbus versions above 2.8.2.
Data was transferred from Harmony to Columbus. This behaviour is improved in Columbus versions above 2.8.2.
Data was imported to ColumbusPlus, the Custer system was available but still the Remote Reference is missing. This further scenario and reasons why are covered here:
http://forums.cambridgesoft.com/messageview.aspx?catid=65&threadid=3773&enterthread=y
In all of the above the data can be exported to the shared file system and the Remote Reference made good manually as is covered here:
http://forums.cambridgesoft.com/messageview.aspx?catid=65&threadid=3767&enterthread=y