Doubt in References and complex datastructures

[Deepak Mallya]

Hi,
   When I try to use complex data structures I get an error saying
Use of uninitialized value in string at C:\Documents and Settings\deepm\My
Documents\practice.pl line 29, <FILE> line 1.

The line of code is as follows:-
for ($i=0;$i<=$#terms;$i++)
{

$wordlistref->{$terms[$i]}->{"postingsref"}->{"$doc"}->{"d1"}->{$termfreq}++;
}

Can anyone help me on this..Do I need to initialise every single hash
???cant I use it as above

Thanks,
Deepak