In the Subscription Properties dialog, if you click the Columns tab and then Rebuild Column List and no list of source columns appears, you may have exceeded the maximum number of connections to the source. Data Replicator waits up to 60 seconds for a connection to the source so it can get and display the available source columns. After that time, it cancels the operation for rebuilding the column list and displays an error message. You can adjust the maximum number of connections allowed for the source from the Advanced Source Properties dialog.
To decrease the possibility that idle pooled connections may prevent the Data Replicator from establishing active connections to other sources or destinations, you can reduce Time Limit settings on the Connection Pools tab of the Service Properties dialog, and you can reduce Maximum Connection Pool Size settings in the Advanced Source Properties and Advanced Destination Properties dialogs.
Contact Stelo if you need to increase the number of connections that your licensing agreement allows.