[Plugin: Yet Another Related Posts Plugin] wp_posts "doesn't support FULLTEXT indexes&

I received this error:

The YARPP database has an error which could not be fixed.Please try manual SQL setup.

And was able to generate the MyISAM yarpp tables, but the following code:

ALTER TABLE wp_posts ADD FULLTEXTyarpp_title(post_title)
ALTER TABLE wp_posts ADD FULLTEXT yarpp_content ( post_content)

produced an error:

#1214 – The used table type doesn’t support FULLTEXT indexes

What should I do?

Thanks.

http://wordpress.org/extend/plugins/yet-another-related-posts-plugin/