This is usually caused by a  incorrect configuration of the RDI.ini file. To fix it perform the following:

1. Open the RDI.ini file, which is generally located in the C:\Program Files\DocLogic\ProDOC folder.

2. Scroll down to the line that states: Host=xxx.xx.xxx.xx

3. Make sure that line is pointing to the correct IP Address of the MySQL Host.  Sometimes it may be pointed to a localhost when it should be pointed towards the server.

If it is pointing to the correct host, the error message should go away.