You are getting this error because the table prefix for Oracle (EVENTSENTRY.) was not configured through the profile editor. When accessing resources in Oracle, one needs to always prefix the table names with the name of the resource user under which they exist.
The resource user used by EventSentry is always called EVENTSENTRY, as such you will need to specify
EVENTSENTRY.
as the prefix. You can configure the prefix through the profile editor (Maintenance -> Profile Editor -> Edit Selected Profile -> Table Prefix) or by setting the XML element <TablePrefix> in the WebReportsConfig.xml file.
After making these changes you should be able to access the web reports correctly.