Windows RT Deployment Error

I created a Windows RT (Windows 8) Metro app, packaged it and tested in dev environment without any problem. However I got below error when installing the package in another machine (a Samsung tablet):

Add-AppxPackage : Deployment failed with HRESULT: 0x80073CFF, To install this application you need either a Windows developer license or a sideloading-enabled system Deployment of package 02897621-4EBE-4E92-9B00-263BAA300DAC_1.0.0.2_x64__32kjnh8rzfyae [Package Full Name] failed because no valid license or sideloading policy could be applied. A developer license (http://go.microsoft.com/fwlink/?LinkId=233074) or enterprise sideloading configuration (http://go.microsoft.com/fwlink/?LinkId=231020) may be required. NOTE: For additional information, look for [ActivityId] 692ada4a-1bf0-0003-86dc-2a69f01bcd01 in the Event Log or use the command line Get-AppxLog -ActivityID 692ada4a-1bf0-0003-86dc-2a69f01bcd01
At line:1 char:236
+ ... $PackageFile; Add-AppxPackage $PackageFile; if(!$?) {exit 8}
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (C:\Users\in..._x64_Debug.appx  :String) [Add-AppxPackage], Exception
+ FullyQualifiedErrorId : DeploymentError,Microsoft. Windows.Appx.PackageManager.Commands. AddAppxPackageCommand
ERROR: FAILED TO INSTALL DEVELOPER PACKAGE!

It turned out that a developer license is required in the tablet although it's not a development machine. One thing interesting is that I built another Windows 8 XAML application based on a solution came with Microsoft Metro app samples, and that application was installed and run successfully in the tablet. It looks like Windows RT has a certificate check process, and developer license is not required if the app's certificate belongs to Microsoft.