Почему возникает ошибка procedure contains an unresolved reference to an object?

CREATE PROCEDURE [dbo].[GetToursList](	
   @toCity nvarchar(30) = null
   , @toCountry nvarchar(30) = null
   ,  @departureDate date
   , @amountNights int
   , @amountAdults int)
AS
BEGIN
--DECLARE @toCityID int  
--DECLARE @toCuntry int
--SET @toCityID = (SELECT Cities.Id FROM dbo.Cities WHERE Cities.Name = @toCity)
--SET @toCuntry = (SELECT Countrys.Id from dbo.Countrys where Countrys.Name = @toCuntry)

SELECT 
hotels.Name as HotelName
,cities.Name as CityName
,countrys.Name as CounrtyName
,Tours.Price
,hotels.Rating as Stars
,hotels.Line as Line
,hotels.DistanceToAirport as DistToAirport
,hotels.DistanceToBeach as DistTobeach
FROM dbo.Tours 
INNER JOIN dbo.Countrys as countrys
ON CountryID = countrys.Id
INNER JOIN dbo.Cities as cities
ON CityID = cities.Id
INNER JOIN dbo.Hotels as hotels 
ON HotelID = hotels.Id
WHERE
(@toCountry is null or(CountryID = (select Countrys.Id from dbo.Countrys where Countrys.Name = @toCountry)))--подчеркивает CountryID
and
(@toCity is null or(CityID =       (select Cities.Id   from dbo.Cities   where   Cities.Name = @toCity)))
END

Procedure: [dbo].[GetToursList] contains an unresolved reference to an object. Either the object does not exist or the reference is ambiguous because it could refer to any of the following objects: [dbo].[Cities].[CountryID], [dbo].[Countrys].[CountryID], [dbo].[Hotels].[CountryID] or [dbo].[Tours].[CountryID]. dbo.GetToursListByCity

(@toCountry is null or(CountryID = (select countrys.Id from countrys where countrys.Name = @toCountry)))

INNER JOIN dbo.Cities as cities
ON CityID = cities.Id

CREATE TABLE [dbo].[Tours] (
    [Id]              INT            IDENTITY (1, 1) NOT NULL,
    [HotelID]         INT            NOT NULL,
    [FromDate]        DATE           NOT NULL,
    [ToDate]          DATE           NOT NULL,
    [Price]           INT            NOT NULL,
    [CityID]          INT            NOT NULL,
    [CountryID]       INT            NOT NULL,
    PRIMARY KEY CLUSTERED ([Id] ASC)
);

CREATE TABLE [dbo].[Cities] (
    [Id]        INT           IDENTITY (1, 1) NOT NULL,
    [Name]      NVARCHAR (90) NOT NULL,
    [CountryID] INT           NOT NULL,
    PRIMARY KEY CLUSTERED ([Id] ASC)
);

CREATE TABLE [dbo].[Countrys] (
    [Id]   INT           IDENTITY (1, 1) NOT NULL,
    [Name] NVARCHAR (90) NOT NULL,
    PRIMARY KEY CLUSTERED ([Id] ASC)
);

CREATE TABLE [dbo].[Hotels] (
    [Id]                INT            IDENTITY (1, 1) NOT NULL,
    [City]              INT            NOT NULL,
    [Rating]            INT            NOT NULL,
    [Name]              NVARCHAR (60)  NOT NULL,
    [DistanceToBeach]   INT            NULL,
    [Line]              INT            NULL,
    [DistanceToAirport] INT            NOT NULL,
    [Discription]       NVARCHAR (MAX) NOT NULL,
    PRIMARY KEY CLUSTERED ([Id] ASC)
);