Backup Error(error Not Found!)

Hi every body

when i try to make backup in location different sql server express 's default location for making backup device it tackes an error

TITLE: Microsoft SQL Server Management Studio Express
------------------------------

Backup failed for Server 'PDSTUDIOSQLEXPRESS'. (Microsoft.SqlServer.Express.Smo)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=9.00.2047.00&EvtSrc=Microsoft.SqlServer.Management.Smo.ExceptionTemplates.FailedOperationExceptionText&EvtID=Backup+Server&LinkId=20476

------------------------------
ADDITIONAL INFORMATION:

System.Data.SqlClient.SqlError: Cannot open backup device 'SQLEXPRESS2005(D:My DocumentsVisual Studio 2005DataBasesBackupSQLEXPRESS2005.bak)'. Operating system error 5(error not found). (Microsoft.SqlServer.Express.Smo)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=9.00.2047.00&LinkId=20476

------------------------------
BUTTONS:

OK
------------------------------
And this is my code for making backup

USE master
GO

EXEC master.dbo.sp_addumpdevice
@devtype = N'disk',
@logicalname = N'SQLEXPRESS2005',
@physicalname = N'D:My DocumentsVisual Studio 2005DataBasesBackupSQLEXPRESS2005.bak'
GO
Server : SQL Server 2005 Express Edition

what is the problem????