I want to brace the the piers with tendons and want to find out forces (or force ratio) in tendons so that the heads of the columns do not move (UX = 0)

I follow the workflow shown in tutorial file csm20_opti_intro_finalstage but im facing some difficulties. Maybe due to chain of cables?

+++++ error no. 210 in program EQU
Equation system not solvable: problem in equation 4
+++++ error no. 217 in program EQU
Equation system not solvable: May be all scalable loadcases act before they
have an effect on a scalable loadcase. This is e.g. the case for bending
moments at the cantilever of a cable stayed bridge before closing the gap.

Column head will not move if there is not any horizontal force acting on it, so horizontal part of cable force have to be in equilibrium. Only cable inclination matter in this case.
CSM cannot solve this since you have 4 cables and 3 columns which leads to 3 equations with 4 unknowns.

Is there a way to edit the system or take other variables to solve the equation?
This system is very easy to solve manually by iteration but i thought that there might be more elegant way?