LGO Closed Traverse, sample practice

Hi all,

Trying to learn the basic of Leica Geo Office and trying to practice a little. I have a closed traverse not undertaken by myself. Ground local coordinates, factor scale 1

G1 set azimuth on G2

G1 forsight S1 and S3

S1 forsight S2 and M10

S2 forsight  S3

S3 foresight G1

Each target has been shot 6 times (3 on both faces).

I create a new traverse, add the stations, calculate and i get :

"Angular and closing misclosure could not be calculated due to missing Control coordinate or unknown azimuth for last forsight azimuth". no matter which method I use

I notice that at S1 it recognise as " Foresight Point Id" M10 that is not a vertex setup of the traverse so I changed it with S2, it shows me all 6 triplets, it doesn't matter which one I choose.

Anyway nothing changes. 

Then I set S3 as Control (fix Pos and Height).  and now traverse recalculate works.

Now the question is...Why? Setting S3 as control, I fix it and it is not affected by the adjustment. Is that right?

I also tried to set as control G2

Or the problem is in the state (never,always,automatic)?. I'm pretty confused about this also. 

Thanks

Edit:

"I also tried to set as control G2"  I was wrong. I have to set S1 and S3 as control other wise it doesn't recalculate the traverse.