Why am I getting this message when I try to save in FMB?

[major_setback]

It's been a long time since I used FMB, and that was with the FB series. i'm just starting to learn again. I made and saved a couple of simple missions and then decided to make one a bit more complicated.
I just spent an hour or two placing objects in a mission and when I tried to save it I got this warning message:

chief '4_chief' contains only one waypoint. Did you forget to set NPC flag?

I have only 2 aircraft in the mission, and each has about 5 waypoints. Neither aircraft (or call sign) is called '4_chief'. The mission is not called that either.

I have a few trucks on the ground with waypoints, but I can't see that they should cause a problem.

Any ideas as to why it won't fly or save? What does the warning mean?

[FG28_Kodiak]

The warning means that you have an actor that has only one waypoint.

To find that actor use the Mission Objects List (View Menu).

[major_setback]

I found it was a fuel truck. I don't know why it required a waypoint.

Now I have another issue though. I get this message when trying to save (and it won't save):

building '0_bld' has unlinked hooks

...and when I delete this building I get the same message for '5_bld' etc.

I'll soon have nothing left of my mission objects. I deleted all trucks and now the buildings are going too.

[FG28_Kodiak]

First if you use an actor like a truck you need a second waypoint, simple set one near the first or look into artillery they don't need a waypoint or into static object there also trucks you can use without need of a wp.

The building '0_bld' has unlinked hooks has to do with larger industrial buildings (these who use more than one part to finish), it's a bug we can nothing do against. Only solution is not to use them.

[major_setback]

OK, thanks a lot for your help.
I'll save my work regularly during the build to save this sort of thing happening.

[huninthesun]

In the current release there are now factory objects under Static (No country)/Building/Industrial - these look identical to the German factory buildings but they can be assembled on the map without the unlinked hooks error.