your $dbh variable is not initialized. grep pointed indirectly to this. you can't call a method on an uninitialized variable. so that's the source of your error.(or maybe you don't have that error, and it's the source of *his* error)

there are a few other things:

$query->start_td(...) should be $query->td(...)
 print $query->end_html; appears more than once. surely you don't mean this...

i can't back grep's suggestions enough: Use strict warnings and diagnostics or die

~Particle ;Þ