According to the "Sterbebücher" (death records) of Auschwitz, Jonas Elekan was murdered there on 22 August 1942. However, in the death registration of Auschwitz had been made an error too: his year of birth was listed as 1887 while this had to be 1897.
The recorded date of death is different from the official date of death of 30 September 1942, as determined by the Dutch Ministry of Justice after the war. For the time being, the website joodsmonument.nl, list only the official dates of death, as published at the time in the "Staatscourant" (Government Gazette) by the Ministry of Justice.
The date of death according to the Death Records (Sterbebücher) of Auschwitz
(just wait a moment till the homepage "Inventarissen" opens, so you might see the certificate down right)