Thanks very much for your help guys. I'vd spent a while messing around with this and it does appear that it is because of the seperate package. To make things simpler I've used a scalar. This is the scene :

I declare the shared var in the main program :

use threads;
use threads::shared;
my $sharedTestVar :shared;
[download]

I then "require" at rumtime the plugin name(which equates to a module) that was passed as a parameter to the program :

...
if(! GetOptions ('plugin=s' => \$plugin,'config=s' => \$instanceName,'
+debug' => \$debug, 'interface=s' => \$interface, 'mcastAddress=s' => 
+\$mcastAddress, 'mcastPort=s' => \$mcastPort, 'file=s' => \$snoopf, '
+remotePcapForwarder=s' => \$remotePCF, 'netprobe=s' => \$netprobe))
{
    usage();
    xit("incorrect options specification", 99);
}

if($debug)
{
    msg("info : turning on debug");
    $ENV{TRACE}=1;
    $DEBUG=1;
}

if(! $plugin)
{
    usage();
    xit("you must supply a plugin name", 98);
}

msg("info : plugin \"$plugin\" will be connected");
eval (require "$PALIBDIR/$plugin.pm");
[download]

I then assign a value to the test scalar :

$sharedTestVar=6;
$DEBUG && msg("init : set sharedTestVar == $sharedTestVar");
[download]

I then create a thread and detach it :

$mcastReaderThread=threads->new(\&doMcastSubscription, $interface,$mca
+stAddress,$mcastPort); 
$mcastReaderThread->detach;
[download]

In the doMcastSubscription sub I increment the scalar :

sub doMcastSubscription
{
...
    while(1)
    {
    my($message,$peer);

    $drop=1 unless $peer=recv($sock,$message,1400,0);
    
    if($drop == 1)
    {
        $DEBUG && msg("recv failed");
        #sleep(2);
    }
    else
    {
        $actualPlugin->processMessage("$message");
    }
        $sharedTestVar++;
        msg("in doMcastSubscription set sharedTestVar == $sharedTestVa
+r");      
    $drop=0;    
    }    
    
    $DEBUG && msg("leaving doMcastSubscription()");
}
[download]

meanwhile I look at the scalar in the main loop of the program :

while(1)
{
...
msg("in main while loop, sharedTestVar == $sharedTestVar");
...
sleep(5);
}
[download]

When I do the above, it works fine, i.e the thread updates the shared scalar with no issue. However, when I move the code that increments the scalar to the file that I "required" at runtime it doesn't work. Here's what the thread is doing now :

sub doMcastSubscription
{
...
    while(1)
    {
    my($message,$peer);

    $drop=1 unless $peer=recv($sock,$message,1400,0);
    
    if($drop == 1)
    {
        $DEBUG && msg("recv failed");
        #sleep(2);
    }
    else
    {
        $actualPlugin->processMessage("$message");
    }
    
    $drop=0;    
    }    
}
[download]

and here's the processMessage sub in UTP.pm :

sub processMessage
{
...
     if($FeedAgent::sendRateStats)
     {
        $sharedTestVar++;
    msg("in processMessage set sharedTestVar == $sharedTestVar");     
+        
     }     
...
}
[download]

I've tried declaring the shared scalar with "our" instead of "my" but this doesn't help either and not not sure what else to do as this is way past my understanding : * (

Any ideas ?? My only thought for a workaround is to use shared memory but I'd rather not

Once again thanks for trying to help, I really appreciate it !!