note the back slash, dereferencing the hash reference

I don't understand what you're trying to say here, and I'm fairly certain this will only confuse other people. The backslash operator takes a reference. You might end up with a reference to a reference if the value in the hash associated with col1 is itself a reference.

... and that's not the OP's problem, anyway. The real problem is attempting to dereference something which is not a reference at all.