Syntax To Use Stored Procedure Parameter

How do I pass my stored procedure value into my query? My first example works, in the second example my parameters are contained in the sql string. How do I expose parameter values to the inner sql string?

Thanks for any help.

Kevin

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This works:
set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[SelectTest]
@StartDate datetime,
@EndDate datetime
AS
BEGIN
SET NOCOUNT ON;
SELECT
DownloadDate, [Project Number], [Project Name], [Expenditure Category],
[Expenditure Type], [Commitments], RevExp
FROM
dbo.OracleDownload
WHERE
DownloadDate BETWEEN @StartDate AND @EndDate
END


This does not:
INSERT INTO ReportTable (ItemDate, ProjectNo, ProjectName, Category, Type, Amount, RevExp)
EXECUTE
('SELECT DownloadDate, [Project Number], [Project Name], [Expenditure Category], [Expenditure Type], [Commitments], RevExp
FROM
dbo.OracleDownload
WHERE
[Project Number] > 0 AND DownloadDate BETWEEN @StartDate AND @EndDate ');