Error Message: ERROR: constraint "fk_FormaPago" does not exist

-- System Information --

Platform: Windows 2000
Version: 5.0
Build: 2195 Service Pack 4

-- Application Information --

Name: pgAdmin II
Version: 1.6.0
Descripton:

Name: pgSchema
Version: 1.6.0
Descripton: PostgreSQL Schema Objects v1.6.0

-- Database Information --

Version: 7.4.0
Descripton: PostgreSQL 7.4 on i686-pc-linux-gnu, compiled by GCC 2.95.4

-- Driver Information --

Name: PostgreSQL
Version: 7.3.115
Descripton: PostgreSQL 7.4 on i686-pc-linux-gnu, compiled by GCC 2.95.4

-- Error Information --

Description: ERROR: constraint "fk_FormaPago" does not exist
Number: -2147467259
Routine: pgAdmin II:frmTable.cmdOK_Click

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Insert your comment:

Agrege una FK, y luego cuando la quiero borrar me muestra ese error...
por que la agrega '' '' al nombre ...?

Example:
BAD --> CONSTRAINT "fk_FormaPago" FOREIGN KEY (id_forma_pago) REFERENCES forma_de_pago (id) ON DELETE NO ACTION ON UPDATE NO ACTION NOT DEFERRABLE INITIALLY IMMEDIATE
GOOD --> CONSTRAINT fk_FormaPago FOREIGN KEY (id_forma_pago) REFERENCES forma_de_pago (id) ON DELETE NO ACTION ON UPDATE NO ACTION NOT DEFERRABLE INITIALLY IMMEDIATE