From the code you're not showing us, I can't make out any reason either. Most likely, somewhere in the code you keep well concealed from our prying eyes, you do the moral equivalent of:

my $foo = '0';
print $foo->{bar};
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Maybe you want to show more relevant and coherent code, and tell us what is debug output and what is code?

Sorry - I had hope that the error message might mean something!
global %$r is a reverse lookup OID number to text
hash keys and values guaranteed no white spaces
here is the code - redundant,
mangled to try to find the error!

 91 sub getsnmp {
 92     my $session = shift;
 93     my $oids    = shift;
 94     my $myresult  = shift;
 95     my $debug   = shift;
 96 
 97     my $result = $session->get_request( -varbindlist => $oids);
 98     if($result) {
 99         if($debug) {
100             printf "%4d getsnmp result\n",__LINE__ ;
101             printf "%4d $_=>\"$$result{$_}\"\n",__LINE__ for (keys
+ %$result);
102         }
103         for $key (keys %$result) {
104             my $value = $$result{$key};
105             $key =~ s/\.\d+$//; ### strip off index at end of stri
+ng
106             my $rkey = $r{$key} or die "bad $key\n";
107             printf "%4d $rkey=>\"$value\"\n",__LINE__ if $debug;
108             print " \$\$myresult{$rkey}=$value;\n ";
109             $$myresult{$rkey} = $value;
110         }
111     } else {
112         return $myresult;
113     }
114     if($debug) {
115         printf "%4d return\n",__LINE__;
116         for(keys (%$myresult) ) { printf "%4d $_=>$$myresult{$_}\n
+",__LINE__}
117     }
118     return $myresult;
119 }
120 1;
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Somewhere (and Perl says in line 109), your data structure is not what you think it is. Use Data::Dumper to get a view of your data structure:

use Data::Dumper;
warn Dumper $result;
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If the line numbers you posted still match up with the error messages you posted in your first post, then the error is in the following line:

$$myresult{$rkey} = $value;
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So you best inspect all three values you have. Most likely, $myresult is 0 instead of whatever you expect:

warn "Parameters on subroutine entry:";
warn Dumper \@_;

warn Dumper $myresult;
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Looks like the module you use to obtain $myresult returns "0" in the case of error and you don't check whether the call was successful

Works OK several times,...

It does? Wow, I can't get that to compile, let alone run, even without Use strict and warnings...what is it supposed to do?