i get System.MissingMethodException in winCE - C#

what this exception:

System.MissingMethodException was unhandled Message: File or assembly name 'System.Windows.Forms, Version=3.5.0开发者_运维问答.0, Culture=neutral, PublicKeyToken=969DB8053D3322AC', or one of its dependencies, was not found.

how i can fix it ?

thank's in advance

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This usually happens when you reference an assembly that has not been deployed to the device. Is the .Net compact framework version 3.5 installed on your device?