Can't Drop Constraint...?

Hello, I have hit the wall here...can't make sense of this one.

I have a script that creates a PRIMARY KEY constraint called PK_tblDRG
CODE:

ALTER TABLE [dbo].[tblDRG]
ALTER COLUMN [record_id] Uniqueidentifier NOT NULL
Go
ALTER TABLE [dbo].[tblDRG]
WITH NOCHECK ADD PK_tblDRG PRIMARY KEY CLUSTERED
(
[record_id]
) WITH FILLFACTOR = 90 ON [PRIMARY]

All is fine with that. I run this to verify:

EXEC sp_pkeys @table_name = 'tblDRG'
,@table_owner = 'dbo' ,@table_qualifier = 'Relational_05Q3'

which returns this:

TABLE_QUALIFIERTABLE_OWNERTABLE_NAMECOLUMN_NAMEKEY_SEQPK_NAME
Relational_05Q3dbotblDRGrecord_id1PK_tblDRG

Now I want to drop the constriant if it exists:

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[PK__tblDRG]') and OBJECTPROPERTY(id, N'IsPrimaryKey') = 1)
ALTER TABLE [dbo].[tblDRG] DROP CONSTRAINT PK__tblDRG

AND I get this in return:

The command(s) completed successfully.

So, lets double check:

EXEC sp_pkeys @table_name = 'tblDRG'
,@table_owner = 'dbo' ,@table_qualifier = 'Relational_05Q3'

AND I STILL GET THIS:

TABLE_QUALIFIERTABLE_OWNERTABLE_NAMECOLUMN_NAMEKEY_SEQPK_NAME
Relational_05Q3dbotblDRGrecord_id1PK_tblDRG

Hmmmmm. Looks like the IF statement didn't do it's job. Ok fine. I'll just kill it myself:

ALTER TABLE [dbo].[tblDRG] DROP CONSTRAINT PK__tblDRG

AND I GET THIS?!?!?!?!

Server: Msg 3728, Level 16, State 1, Line 1
'PK__tblDRG' is not a constraint.

What am I not getting here? Is it me...I can take If I am a bone head here.

Any help would be appreciated. Thanks!