What is the meaning of these two phrases?

Hi all, recently I'm doing a delete form where the administrator has to full-right to delete and edit the profiles stored.
But I'm having problem when I deleting a record.
My problems are as follows:

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource
Warning: mysql_free_result(): supplied argument is not a valid MySQL result resource

These warnings prompt really make me mad!
I do not know what went wrong with my code.

--Kindly reply my thread as soon as possible.--
Your helps will be much appreciated.
Thanks!

These warnings indicate that there is something wrong with your SQL.

Take another look at your SELECT statement. Try running your query in the database itself (using something like phpmyadmin) and see what happens.

When it doesn't work, post a piece of your code here...