[Koha] Solr

Hi! Im using koha 3.12 e im trying to use solr instead of zebra as search engine. Everything seems fine except that solr is not indexing the records correctly. Each record looks like this: <doc> <str name="id">biblio_1</str> <str name="recordid">1</str> <str name="recordtype">biblio</str> <str name="srt_ste_title"/> <str name="srt_str_author"/> </doc> Any ideas?