Your errors suggests that provide us the code before this line which may has anything to do with this variables.
Both of the code below works.:
$hashref = {  '$/ 11' => 'a'};
$fieldnum= '$/ 11';
$value = $hashref->{$fieldnum};
print "$value";

[download]
and 
$hashref = { a => '$/ 11' };
$fieldnum= 'a';
$value = $hashref->{$fieldnum};
print "$value";

[download]

In reply to Re: Argument isn't numeric in hash element by artist
in thread Argument isn't numeric in hash element by Stephen Toney

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