I have found the problem. I've replaced a Storable DB driver with a SQLite driver and my code is now working. 
my $dbh = DBI->connect('dbi:SQLite:dbname=hist_mod.db');

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I am not sure what was the reason to my problems with Storable DB, but for my task it does not meter which type of DB to use.

Thanks to everybody for your help and suggestions

In reply to Re^2: Perl DBI: problems inserting data to a table by homeveg
in thread Perl DBI: problems inserting data to a table by homeveg

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