Search Clause: where DATE >= 'YYYY-MM-DD' FAILS

[Duncan Groenewald <duncangroenewald@xxxxxxxxxx>]

Any suggestions as to why the following search clause fails to return 
any rows ?

select P.Description, D.StartDate, D.DueDate,D.PromToRelActual
from ProjectWBS P, ProjectWBSDetail D
where ProjectCode = '011'
and D.ID=P.ID
and D.PromToRelActual >= '2006-11-01'
and D.PromToRelActual < '2006-12-01'
order by D.PromToRelActual

My workaround was the following:

select P.Description, D.StartDate, D.DueDate,D.PromToRelActual
from ProjectWBS P, ProjectWBSDetail D
where ProjectCode = '011'
and D.ID=P.ID
and cast(D.PromToRelActual as varchar(10)) >= '2006-11-01'
and cast(D.PromToRelActual as varchar(10)) < '2006-12-01'
order by D.PromToRelActual

Table definitions are:

create table ProjectWBS
   (ID              numeric          NOT NULL,
    ParentID        numeric          ,
    IndexNo         int              NOT NULL,
    Type            int              NOT NULL, 
    Description     varchar(64)      NOT NULL,
    ProjectCode     varchar(12)      NOT NULL,
    Status          int              DEFAULT 0,
    TStamp          timestamp        DEFAULT CURRENT_TIMESTAMP ,    
    PRIMARY KEY (ID)
)

create table ProjectWBSDetail
   (ID                  numeric         NOT NULL,
    Description         long varchar    ,
    Release             varchar(64),
    StartDate           date            ,
    DueDate             date            ,
    ChiefProg           varchar(64)     ,
    Owner               varchar(64)     ,
    DevEstimate         float           DEFAULT 0.0 NOT NULL,
    Actual              float           DEFAULT 0.0 NOT NULL,
    Priority            int             DEFAULT 0 NOT NULL,
    Complexity          int             DEFAULT 2 NOT NULL,
    ReqGatherStatus     varchar(12)    ,
    ReqGatherPlan       date           ,
    ReqGatherActual     date           ,
    ReqWalkThroStatus   varchar(12)    ,
    ReqWalkThroPlan     date         ,
    ReqWalkThroActual   date         ,
    DesignStatus        varchar(12)    ,
    DesignPlan          date             ,
    DesignActual        date             ,
    DesignInspStatus    varchar(12)    ,
    DesignInspPlan      date          ,
    DesignInspActual    date          ,
    BuildStatus         varchar(12)    ,
    BuildPlan           date             ,
    BuildActual         date             ,
    BuildInspStatus     varchar(12)    ,
    BuildInspPlan       date             ,
    BuildInspActual     date             ,
    PromToRelStatus     varchar(12)    ,
    PromToRelPlan       date             ,
    PromToRelActual     date             ,
    TStamp               timestamp        DEFAULT CURRENT_TIMESTAMP ,
    PRIMARY KEY (ID)
);
alter table ProjectWBSDetail add CONSTRAINT ProjectWBSDetailFK01
FOREIGN KEY (ID) REFERENCES ProjectWBS(ID);