Console error

Hello, dear programmers, I have a bug in the console when launching the project “Assets / MFPS / Scripts / Misc / AI / bl_SimpleAI.cs (29.13): error CS0246: The type or namespace name” NavMeshAgent 'could not be found. Are you missing `UnityEngine.AI 'using directive?" Do not tell me what to do?

Maybe it is to late for answer for You but if someone else get to this problem … :
in console You have list of files that have that issue on top od each file add
`UnityEngine.AI 'using directive
and when unity compiles it is possible that new ones will emerge, then add to them also

Cheers