There are 3 objects, and every object has 3 constraints. Use the next system to calculate

$$
JV + B = 0
$$
$$
lambda = (JM^{-1}J^{T})^{-1}(-JV – B)
$$
$$
Delta V = M^{-1}J^{T}lambda
$$
As a result of there are 3 objects and every object has 3 constraints

for every constraint:
$$
J_{(1 instances 18)} = start{vmatrix}
-vec{n}^{T} & -(vec{r_{a}} instances vec{n})^{T} & vec{n}^{T} & (vec{r_{b}} instances vec{n})^{T} & left| 0 proper| _{(1 instances 3)} & left| 0 proper| _{(1 instances 3)}
finish{vmatrix}
$$
$$
M^{-1}_{(18 instances 18)} = start{vmatrix}
M_{a}^{-1} & 0 & 0 & 0 & 0 & 0
0 & I_{a}^{-1} & 0 & 0 & 0 & 0
0 & 0 & M_{b}^{-1} & 0 & 0 & 0
0 & 0 & 0 & I_{b}^{-1} & 0 & 0
0 & 0 & 0 & 0 & M_{c}^{-1} & 0
0 & 0 & 0 & 0 & 0 & I_{c}^{-1}
finish{vmatrix}
$$
$$
M_{n} , I_{n} in R_{(3 instances 3)} left{ n = a,b,c proper}
$$
So the ultimate equation is：
$$
lambda_{(6 instances 1)} = (J_{(6 instances 18)}M^{-1}_{(18 instances 18)}J^{T}_{(18 instances 6)})^{-1}(-J_{(6 instances 18)}V_{(18 instances 1)} – B)
$$
$$
Delta V_{(18 instances 1)} = M^{-1}_{(18 instances 18)}J^{T}_{(18 instances 6)}lambda _{(6 instances 1)}
$$
The issue is: this system is right when utilizing lower than 5 constraint factors. However when the constraint factors are higher than or equal to five, the determinant of the matrix can be equal to 0.
Program error, why?