EntityFramework Procedure or function '' expects parameter '', which was not supplied.

Question

I apologise for asking just a basic question, however I cannot find the cause of this error.

I am using Entity Framework to execute a Stored Procedure, and I am passing in four parameters, however the SQL Database seems to reject them. Can anyone point me in the right direction?

My code:

ObjectResult<SearchDirectoryItem> resultList = container.ExecuteStoreQuery<SearchDirectoryItem>("SearchDirectoryEntries",
            new SqlParameter("@DirectoryId", search.DirectoryId),
            new SqlParameter("@Latitude", point.Latitude),
            new SqlParameter("@Longitude", point.Longitude),
            new SqlParameter("@Range", search.RangeMiles));

Which produces the error:

Procedure or function 'SearchDirectoryEntries' expects parameter '@DirectoryId', which was not supplied.

The SQL generated is:

exec sp_executesql N'SearchDirectoryEntries',N'@DirectoryId int,@Latitude decimal(7,5),@Longitude decimal(6,5),@Range int',@DirectoryId=3,@Latitude=53.36993,@Longitude=-2.37013,@Range=10

The stored procedures is:

ALTER PROCEDURE [dbo].[SearchDirectoryEntries]
@DirectoryId int,
@Latitude decimal(18, 6),
@Longitude decimal(18, 6),
@Range int

Many Thanks.