Problem to detach schema

TITLE: Microsoft SQL Server Management Studio
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Detach database failed for Server 'WIN-O3CHI1MHE5D\SS2012'.  (Microsoft.SqlServer.Smo)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=11.0.3000.0+((SQL11_PCU_Main).121019-1322+)&EvtSrc=Microsoft.SqlServer.Management.Smo.ExceptionTemplates.FailedOperationExceptionText&EvtID=Detach+database+Server&LinkId=20476

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ADDITIONAL INFORMATION:

An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)

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Cannot detach the database 'my_schema' because it is currently in use. (Microsoft SQL Server, Error: 3703)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft%20SQL%20Server&ProdVer=11.00.2218&EvtSrc=MSSQLServer&EvtID=3703&LinkId=20476

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BUTTONS:

OK
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Many Thanks & Best Regards, Hua Min