Typeahead

typeahead prefix=<string> count=<int> [max_time=<int>] [<index-specifier>] [<starttimeu>] [<endtimeu>] [collapse]

For index=? here, because we have "index" in DEFAULT_FIELD, it will cause error if I add it to TYPEAHEAD_OPT.
If I define a rule like DEFAULT_FIELD EQ value, the index one is still not working.
How can I solve this problem?