While I am unable to nail down the exact nature of your problem, I have a suggestion. Assuming you have access to Access, does your sp2 run fine from within Access? That may be the quickest way to identify the cause of your error.

Also, I am seeing the following in your code

$db-> Sql( "execute  Sp2  2004/05/16" )
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I think you might want to escape your date properly. In Access you usually do like so --

my $date = "#2004/05/16#";
$db-> Sql( "execute  Sp2  $date" )
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Note the use of the # signs bookending the date.