If Mercury does not automatically open the CSD database when started, then it may be having difficulty locating the appropriate database files. In such a case, Mercury can be pointed to the correct location by using the Databases->Database Locationmenu option.
Mercury will also check the environment variable CCDC_TOOLKIT_ASER_DATABASE. If this points to an ASER database, the database will be opened.
For example, on Windows:
and on Unix (C shell):
setenv CCDC_TOOLKIT_ASER_DATABASE /home/cdrom/csd/as5??be
where ?? = the database version number you have installed.