cannot connect to database through ECPG but can through psql

I'm a relative newbie to Postgres but I've asked a few colleagues about
this problem without a solution, so I'm hoping someone on the list serve
can help.

The problem arose when I move to an upgraded operating system, an upgraded
version of Postgres, and when I dump a database out of the old machine and
restore it on a new machine.

Old: RedHat 5.9, Postgres 8.1.23
New: RedHat 6.6, Postgres 9.2

Everything worked fine with the old setup. With the new setup, I can
access my database through psql command-line. However, I have a compiled
program called 'Shefdecode' that makes queries to the database through ECPG
and this program cannot access the database. I get errors:

"Postgres error -220" and
"SQL STATE = 08003" (User manual says this means "The program tried to
access a connection that does not exist.")

Although I don't have the source for the Shefdecode program, I know it uses
the environment variables PGUSER and PGHOST and also gets passed the
database name. I've checked to make sure these are correct.

What else should I look for to try to determine the cause of this error?

Any ideas would be greatly appreciated.

Seann