sql exception during delete virtual wiki in Oracle

Can't delete virtual wiki in Oracle.
stack trace is below:

Caused by: com.xpn.xwiki.XWikiException: Error number 3402 in 3: Exception while delete wiki database a22i
Wrapped Exception: ORA-00950: invalid DROP option

at com.xpn.xwiki.store.XWikiHibernateStore.deleteWiki(XWikiHibernateStore.java:274)
at com.xpn.xwiki.store.XWikiCacheStore.deleteWiki(XWikiCacheStore.java:498)
at com.xpn.xwiki.plugin.wikimanager.doc.Wiki.delete(Wiki.java:63)
at com.xpn.xwiki.plugin.wikimanager.WikiManager.deleteWiki(WikiManager.java:772)
at com.xpn.xwiki.plugin.wikimanager.WikiManagerPluginApi.deleteWiki(WikiManagerPluginApi.java:229)
at com.xpn.xwiki.plugin.wikimanager.WikiManagerPluginApi.deleteWiki(WikiManagerPluginApi.java:261)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:295)
at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:245)
... 100 more
!!!:getSchemaFromWikiName, wikiName=xwiki
isMainWiki: true