This is the error I keep getting repeatedly when compiling my other scripts.
c:\Users\Unity Realm\Documents\AAUnity\Assets\PlayMaker\Actions\EnableFSM.cs(24,24): Error CS0012: The type 'UnityEngine.MonoBehaviour' is defined in an assembly that is not referenced. You must add a reference to assembly 'UnityEngine, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'. (CS0012) (Assembly-CSharp)
It is rather shocking that that error could go unoticed on a recent release for a paid product.