I have another related issue here:
Building a Hash of arrays from a hash of arrays based on a list?
A full explanation is here.

This problem: I am trying to create a hash or list of references of dates that have a hash table of sedols mapped to the total amount of shares traded. I need for every unquie day associated with it a hash table of unique sedols mapped to the the total amount traded for each. .... I am getting:

Type of arg 1 to keys must be hash (not hash elem) at line 556

this is the line:

foreach $sedolelement (keys $tradedatehash{$tradedatemarker}) {
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what is wrong?????

# ------ Build_tradedatehash_sedolandtotalsharesarray ----- 

sub Build_tradedatehash_sedolandtotalsharesarray($$$$) {

#$j = shift;
my $tradedate = shift;
my $sedol = shift;
my $shares = shift;
$condition = "";
my $myfirstflag = shift;
if ($myfirstflag eq "YES") {
    my $j = 0; 
} else { my $j = 1;}
print "$tradedate $sedol $shares \n";

    $count = 0;    
    if ($j == 0) {
        $tradedatehash{$tradedate} = {$sedol => $shares}; 
        foreach $tradedatemarker (%tradedatehash) {
            print "For the date: $tradedatemarker \n\tsedols \t total 
+shares\n\n";
            foreach $sedolelement (keys $tradedatehash{$tradedatemarke
+r}) {
                print "\t  $sedolelement \t $_\n";
            }
            print "\thave traded.\n";
        }
    } else {
    #print "this is j $j\n";
        foreach $tradedatemarker (${$tradedatehash{$tradedate}}) {
            if (exists $tradedatehash{%tradedate}) {
                print " yes yes yes $tradedatemarker\n!";
                foreach $sedolelement (keys $tradedatehash{$tradedatem
+arker}) {
                    if (exists $sedol) {
                        $tradedatehash{$trademarker}->{$sedol} += $sha
+res;
                    } else {
                        $tradedatehash{$trademarker} = {$sedol => $sha
+res};
                    }#
                }
            } else {
                $tradedatehash{$tradedate} = {$sedol => $shares};
            }
        }
        foreach $tradedatemarker (${$tradedatehash{$tradedate}}) {
            print "For the date: $tradedatemarker \n\tsedols \t total 
+shares\n\n";
            foreach $sedolelement (keys $tradedatehash{$tradedatemarke
+r}) {
                print "\t  $sedolelement \t $_\n";
            }
            print "\thave traded.\n";
        }
    }
} # end sub Build_tradedatehash_sedolandtotalsharesarray
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