I belive this is a problem with my Perl syntax

Did you verify the environment at the point of failure? Honestly, we are talking whether or not a certain environment variable is or is not defined at a particular point of the program. This can be verified easily. Also, you can verify whether this environment variable is or is not defined at the start of the program (to cover the case where your program is deleting it from the environment). What did you find out in this respect?