Good Morning Guys

I have the Following statement, that works well when i test it alone

Code:
declare @Results int exec [dbo].[sp_RestoreDatabase_O_Booking] 'MasekoTS','MasterDatabase', @Results OUT
But now, i want to include this code in a Stored Procedure and i tried to do it like this

Code:
SELECT @sql1 = 'Declare @Results int exec [dbo].[sp_RestoreDatabase_O_Booking] ''' + @DB + ''', ''' + @Filename + '''@Results OUT'''
execute ( @sql1 )

and i get the Following Error

Msg 105, Level 15, State 1, Line 1
Unclosed quotation mark after the character string 'sp_RestoreDatabase_O_Bookin'.
Msg 102, Level 15, State 1, Line 1
Incorrect syntax near 'sp_RestoreDatabase_O_Bookin'.
Thank you