Perl LDAP script error "Can't call method "dn" on an undefined value"

[anakin30]

i received below error when i run my code

The script generate result if the input file contains less then 10 users, however the error trigger if the input file contain more than 10 users

i appreciate if anybody can advice, how to rectify the error

Can't call method "dn" on an undefined value at ExportAttribute2.pl line 45, <TEST> line 991.

i have marked the error , line number with the comment # in the below code for your reference

$TEST = 'C:\Perl\project\export\20130402\test.txt';
#$TEST = 'C:\Perl\project\export\20130402\users.txt';
$outputfile = 'C:\Perl\project\export\20130402\result.csv';

open (FH, ">$outputfile") or die "$!";
print FH "uid,SN,GIVENNAME,uniSALUTATION,Displayname\n";

my $adHost = "ldap.uni.com";
my $adUsr = "uid=myscript,ou=users,o=uni.com";
my $adPass = "Myscript2012";
my $query = "(objectclass=uniperson)";
my @attrs = qw(uid SN GIVENNAME uniSALUTATION Displayname);
my $ldap = Net::LDAP->new($adHost) or die $!;
my $mesg = $ldap->bind($adUsr, password =>$adPass);
my $page = Net::LDAP::Control::Paged->new( size => 1000 ) or die $!;

open(TEST) or die("Could not open log file.");
foreach $line (<TEST>) {
chomp($line);
#print "$line \n";#}
#while (1) {            
my @args = ( base => 'ou=users,o=uni.com' , scope => 'sub', filter => 
+$line, attrs => \@attrs, control => [ $page ],);
$mesg = $ldap->search ( @args ) or die $!;
#while (my $entry = $mesg->shift_entry() ) {
#uid,SN,GIVENNAME,uniSALUTATION,Displayname
my $entry = $mesg->shift_entry();
my $entrydn = $entry->dn();   #line 45 the error triggered here
my $uid = $entry->get_value ('uid');
my $SN = $entry->get_value ('SN');
my $GIVENNAME = $entry->get_value ('GIVENNAME');
my $uniSALUTATION = $entry->get_value ('uniSALUTATION');
my $Displayname = $entry->get_value ('Displayname');

print FH "$uid,$SN,$GIVENNAME,$uniSALUTATION,$Displayname\n";
}

please advice me how to get rid of the error above. I need to export 3000 users based on userID from input file with the selected attributes from LDAP using this script"