3D cable net

Hello!
I'm trying to calculate the max deformation and the max axial force of a cable net 3D, under a (point) wind load and pretension, using first "Large-Deformation" component and then "Analyze Th.II" for the forces. In the 2D cable net there wasn't any problem, but in this if I set the pretension over about "1" the cables explode, but the value that I need is "2.6". May it could be a problem of joints between the elements? 

Thanks in advance,

Sofia