How to make our fulltext indexing?

how can i make our fulltext indexing?
our encoding is GB2312 or GBK,
but after I changed
"default encoding"
“word fragment index” option,and I set the field index to “text”,I can not see any speed improvement.

the admin xql is:
<A HREF=“[“Document”,“Document/ZhengWen”,“A”,“10”,“standard”” TARGET=_blank>“Document”,“Document/ZhengWen”,“A”,“10”,“standard”)

the result is:
<?xml version="1.0" ?>
- <ino:response xmlns:ino=“” xmlns:xql=“”>
- <ino:message ino:returnvalue=“8257”>
<ino:messagetext ino:code=“INOXHE8257”>Conversion failed, output encoding -1, error code 304.</ino:messagetext>