Table not found in PHP-PDO environment with Driver PGSQL

Question

The connection to the PostGreSQL-DB works without error. The SQL-Statement

select * from sessions;

returns the error "Relation sessions does not exist".

If the following statement is exececuted at this place:

select * from pg_catalog.pg_tables where tablename = 'sessions';

than one record is found:

schemaname: appgeenlabor, tablename: sessions,
tableowner: forum, hasIndexes: true, 
hasrules: false, hastriggers: true, 
rowsecurity: false

The database is connected with user "forum".

Which conditions can avoid the selection of the table session?

Note: the table sessions has been created by the tool "pgloader" which converts a MySql table into a PostGreSQL table.