How to run all the webtests from commandline

I have dll file for webtests. I used the below command to execute all my webtests

mstest /testcontainer:"MyPath\PostAccessToken.dll" /resultsfile:MyResultPath\MyResults.trx

When i tried the above command I got the below message.

Microsoft (R) Test Execution Command Line Tool Version 12.0.21005.1 Copyright (c) Microsoft Corporation. All rights reserved.

Loading PostAccessToken.dll... Starting execution... No tests to execute.

My dll file contents are

[assembly: TargetFramework(".NETFramework,Version=v4.5", FrameworkDisplayName=".NET Framework 4.5")]
[assembly: AssemblyTitle("PostAccessToken")]
[assembly: AssemblyDescription("")]
[assembly: AssemblyConfiguration("")]
[assembly: AssemblyCompany("")]
[assembly: AssemblyProduct("PostAccessToken")]
[assembly: AssemblyCopyright("Copyright \x00a9  2016")]
[assembly: AssemblyTrademark("")]
[assembly: ComVisible(false)]
[assembly: Guid("2227ff72-2254-4e3e-af43-76a98b558c80")]
[assembly: AssemblyFileVersion("1.0.0.0")]
[assembly: Debuggable(DebuggableAttribute.DebuggingModes.DisableOptimizations | DebuggableAttribute.DebuggingModes.EnableEditAndContinue | DebuggableAttribute.DebuggingModes.IgnoreSymbolStoreSequencePoints | DebuggableAttribute.DebuggingModes.Default)]
[assembly: CompilationRelaxations(8)]
[assembly: RuntimeCompatibility(WrapNonExceptionThrows=true)]

how can I run all webtests from this library by one command?