The command "Flatten Image" is not currently available.

Hi

I have an automation plugin for CC 2014 and trying to flatten image by code. It is giving this issue - "The command "Flatten Image" is not currently available."

    SPErr error = kSPNoError;

    error = sPSActionControl->Play(&result, eventFlattenImage, NULL, plugInDialogDisplay);

Can anyone please guide what could be the reason for this error and what does this error means?

Thanks