Error to add Feeds

HI,

I´m using joomla 1.5.22 .
I install Ninja Rss to content.
I try to add new feed, I get this error:
Error Saving:
Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/terminaltv/www/libraries/joomla/database/database/mysql.php on line 344

thanks any help,

Eduardo D.S.
Brazil

02 Jan 12

i am getting the same error without the mysql warning bit . i just get error saving.