Have you tried doing an explicit bind_param() before calling execute() ? Something like this:

use DBI qw(:sql_types);    # make sure DBI gives you access to sql_typ
+es strings

$Array[0] = undef;
$sth = $dbh->prepare("INSERT into MYTABLE (mydate) VALUES(?)");
$sth->bind_param( 1, $Array[0], SQL_DATETIME );   # forces the data ty
+pe
$sth->execute;   # no args needed here now.
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I don't know if that will help (I don't use ODBC), but if you haven't tried it, it's worth a try.