Com_Reservations + mysql Error

[rentasite]

Hi,
On a site, with IOS Reservations installed, i face the following problem. The error is seen on the English version. Greek works well.  Any idea?

mysql Error [1064] : EXECUTE
URI: index.php?option=com_reservations&Itemid=64

Message: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '5)' at line 1
SELECT elid, translation FROM elx_res_translations WHERE type = 'loctitle' AND language = 'english' AND elid IN (,5)

Thanks

[rentasite]

The error disappeared now, without doing anything...  But what could caused it?