pg_dump not working - Mailing list pgadmin-support

dear Friends,
I am a new comer to PostgerSQL.
I have PostgreSQL  7.x.x on windows 2000.
When i try to backup a database using
pg_dump databasename >backupfile
It gives Pareser Error at or "pg_dump" at character1

If someone can help that will be great.

Regards,
Kedar hukeri