Thanks guys, It seems to fail if I use it in a union where there are multiple select stmts. Is it because I am using too many bind variables? I am not sure why but here is the sql code that it fails on. All the other code is the same, only sql code is different, The ERROR I wrote on the bottom of the code:

my @intervals = (
["{ts'2012-07-01 00:00:00.000'}", "{ts'2012-07-02 00:00:00.000'}","{ts
+'2012-07-01 00:00:00.000'}", "{ts'2012-07-02 00:00:00.000'}"],
["{ts'2012-07-02 00:00:00.000'}", "{ts'2012-07-03 00:00:00.000'}","{ts
+'2012-07-02 00:00:00.000'}", "{ts'2012-07-03 00:00:00.000'}"]);


my $dbh = DBI-> connect('dbi:ODBC:DSN=WCPM-DB1;UID=TEST;PWD=pass') or 
+die "CONNECT ERROR! :: $DBI::err $DBI::errstr $DBI::state $!\n";

my $sql2 = <<EOSQL;
SELECT *, DATEDIFF(n,MIN_TIME,MAX_TIME) AS MINS_DIFF 
        FROM
            (SELECT Login_ID, MIN(TimeStamp) AS MIN_TIME,MAX(TimeStamp
+) AS MAX_TIME
            FROM 
                (SELECT Login_ID,  AuditChrt_TimeStamp AS TimeStamp,
                    Patient_ID
                FROM         
                    (SELECT Login_ID, AuditChrt_TimeStamp, Patient_ID
                    FROM TopsData.dbo.AUDT_AuditChrt
                    WHERE Login_ID IN ('ZZZZZ0004R','ZZZZZ00050','ZZZZ
+Z0006J','ZZZZZ0006P','ZZZZZ0007A')
                                    AND AuditChrt_TimeStamp > ?    
                                    AND AuditChrt_TimeStamp < ?) AS A
    UNION ALL
            SELECT Login_ID, AuditMedication_TimeStamp AS TimeStamp, P
+atient_ID
            FROM 
                (SELECT Login_ID, AuditMedication_TimeStamp, Patient_I
+D
                FROM TopsData.dbo.AUDT_AuditMedication
                 WHERE Login_ID IN ('ZZZZZ0004R','ZZZZZ00050','ZZZZZ00
+06J','ZZZZZ0006P','ZZZZZ0007A')
                                    AND AuditMedication_TimeStamp > ? 
+       
                                    AND AuditMedication_TimeStamp < ?)
+ AS B
            ) AS A
    GROUP BY Login_ID) AS A;                            
EOSQL
my $sth = $dbh->prepare($sql2);

foreach my $interval (@intervals) {
    $sth->execute(@$interval);
    my @row;
    while (@row = $sth->fetchrow_array) {  # retrieve one row at a tim
+e
        print  join(", ", @row), "\n";

ERROR: DBD::ODBC::st failed: Conversion failed when converting data an
+d/or time from character string.
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