[PHP] mysql_num_rows()

[PHP Junkie]

Ave,

In one of my scripts, I'm getting the error:

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result
resource in /Library/WebServer/Documents/limiteduse.net/dumptoday.php on
line 56

Iım not clearly sure why. Iım running PHP5 with mySQL 4 ... Is there a
compatibility issues somewhere?