OpenRowSet procedure: is not a valid identifier! Need someone to check code.

Hi,
I have problem to insert Openrowset method into procedure as getting an error "Is not invalid identifier".
Openrowset works if it is execute with normal query.

USE [TestDB]
GO

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[procTEST]

AS
DECLARE @TEST VARCHAR(MAX)
SET @TEST = 
'
Select COUNT(*) FROM OPENROWSET(''Microsoft.ACE.OLEDB.12.0'', ''Excel 12.0;Database=C:\Users\test\Desktop\test.xlsx;HDR=YES;IMEX=1'', ''SELECT * FROM [Sheet1$]'') as a
'
EXEC @test

Select allOpen in new window

Thanks in advance for help!