I think your basic error was to try to put too much into the variable offset. You are asking it to do too much. Here is a more verbose version showing which variables do what. We are not worried about shortest code here! An "experienced" Perl programmer would have used a regular expression to parse out the piece he wanted. See the last lines of the code below.

my $line='PSAPPSRV.26476584 (6) 01/02/19 06:30:30 GetCertificate(3) Re
+turning context. ID=PTWEBSERVER, Lang=ENG';
my $SpaceChar = ' ';
my $offset = 0;
my $start_at=0;
my $space_ctr = 0;
my $result;

while ($space_ctr < 4) {
   $offset = index($line, $SpaceChar, $start_at); # $offset
   $result = substr $line,index($line, $SpaceChar, $start_at);
   $space_ctr++;
   $start_at = $offset + 1; 


 print "Substr($offset) = $result \n"; 
 print "space #:$space_ctr found at offset: $offset \n";
 }

# using a regex to parse out the piece we want:
$line =~ m/\S*\s+\S*\s+\S*\s+\S*\s+(.*)/ ;
                   # \S* is zero or more NON space chars. \s+ is one o
+r more SPACE chars. (.*) is everything after the 4th space. saved in 
+$1 for later use.
my $wanted_substr = $1;
print "Wanted String= $wanted_substr \n";
exit 1;
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