2nd-level contrasts

Dear all, 

I'm new to CONN, and not sure what I'm doing with my results. I have 2 groups (Group_A (n=16) ; Group_B (n=14)) defined in "Setup Covariates (2nd-level)" and 2 sessions (Sess_1 ; Sess_2) defined in "Setup Conditions". 
Then I have a clinical score (Score) defined in "Setup Covariates (2nd-level)", and I created an "All Subjects" group, also defined in "Setup Covariates (2nd-level)".

I try to see what's different between the two sessions depending on my clinical score. 

1. I choose "All Subjects" , "Score" [0 1] / "Sess_1" , "Sess_2" [-1 1]

2. I choose "Group_A" , "Group_B" , "Score" [0 0 1] / "Sess_1" , "Sess_2" [-1 1]

Why do I have differents results with these two contrats ? 

Thank you for your help in advance,
Best regards,
Louis