Restoring PostgreSQL Database Backup

Respected,

I am using the following version of PgAdmin and PostgreSQL

PgAdmin Version: 1.8.4 (June 4 2008, rev:7358)
PostgreSQL: 8.3.13

Problem: I have a data base backup file created in PosgtreSQL 8.4.14, when
I restore it in PostgreSQL: 8.3.13 on a database (by using pgadmin-iii,
right click on the data base to restore file) it shows the following error:

D:\PostgreSQL\8.3\bin\pg_restore.exe -h localhost -p 5432 -U postgres -d
aflprod -v "E:\backup af 20140201.backup"
pg_restore: [archiver] unsupported version (1.11) in file header

Process returned exit code 1.

I need help how to handle this issue.

Thanks,

Rizwan