And is $ref a typo or your actual code?

Try gnorks advice, and let the offending line look like

foreach my $key (keys(%$param)) {
[download]

Or try to be more specific in your questions, always mentioning

what

code stripped down to a minimum

where

in the code

which results

e.g. error messages you got

why

Problem you try to solve

(not necessarily in this order and on occasion deeply nested :)

Edit: fixed $% to %$