Consider the following scenario:
- You start Microsoft SQL Server 2008 Management Studio.
- You start Replication Monitor.
- You expand a publisher and then click a publication.
An error occurred while retrieving the publication data. Unable to case object of type 'System.DBNull' to type 'Microsoft.sqlserver.Replication.PublisherMonitor.
This issue occurs if you click the publication before the list of publishers is populated.
To work around this issue, wait until the list of publishers is fully populated before you click a publication.
Typically, the issue that is mentioned in the "Symptoms" section occurs when many servers are listed as publishers. The publisher list may also populate slowly if the servers are busy or are on slow network connections.