Exec Stored Proc

Hi Guys, I created the following stored proc which calls another stored procs as shown below.
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Create Procedure [dbo].[rpt_CompareDB](@tbl_name varchar(400),@DB_name1 varchar(400),@DB_name2 varchar(400))

AS

declare @result1 varchar(8000),

@result2 varchar(8000),

@table_name varchar (400),

@DB1 varchar(400),

@DB2 varchar(400),

@table_final1 varchar(400),

@table_final2 varchar(400),

@DB_detail1 varchar(400),

@DB_detail2 varchar(400)

set @table_name = @tbl_name
set @DB1 = @DB_name1

set @DB2 = @DB_name2

set @DB_detail1 = @DB1 + '.mfgq_live'

set @DB_detail2 = @DB2 + '.mfgq_live'

set @table_final1 = @DB_detail1 + '.dbo.' +@table_name

set @table_final2 = @DB_detail2 + '.dbo.' +@table_name

exec GetColumnNamesString @DB_detail1,@table_name,@result1 output

exec GetColumnNamesString @DB_detail2,@table_name,@result2 output

exec CompareTables @table_final1,@table_final2,@result1,@result2


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but, when I tried to excute it, I am getting an error.

Here is how I'm trying to exec the stored proc.

execute dbo.rpt_CompareDB

@tbl_name = 'Attribute'

,@DB_name1 = 'Green'

,@DB_name2 = 'devlue02'

FYI, It works fine if you run the query itself instead of executing the stored proc.

Any idea is appreciated