So I changed

     $node = $ARGV[1];
     $interface = $ARGV[3];

and added

warn "Supplied arguments: ",join(",",map { "'$_'" } @ARGV);
warn "Node is '$node', interface is '$interface'.";
and
  print logfile " arg0 '$ARGV[0]'\n";
  print logfile " arg1 '$ARGV[1]'\n";
  print logfile " arg2 '$ARGV[2]'\n";
  print logfile " arg3 '$ARGV[3]'\n";

and I get the following output in the logfile 

0,MyNode
1,MyNode
2,25
3,25
 arg0 'MyNode'
 arg1 'MyNode'
 arg2 '25'
 arg3 '25'
node:'MyNode'
IF:'25'

and on console

Supplied arguments: '25','25' at IfIndex_to_IfDesc_v2.pl line 44.
Node is 'MyNode', interface is '25'. at IfIndex_to_IfDesc_v2.pl
line 45.
Net::SNMP=HASH(0x184bce8)Result ERROR:: No response from remote host '
+MyNode'.
[download]

Thank you
JB