Errors after SAP2000 model locks

Hello,

I'm working with G interacting between Grasshopper and SAP2000.
Everything works fine, I can bake multiple times my GH model and SAP updates with no problems.

All that until I run the analysis either by SAP or using the SAP Solver. First time works perfect but when I try to change something, the Solver fires and I keep getting errors in rhino which the last of them is 

Unable to extract results for joint ggGHn5535

And the others are errors for every single frame.

SAP opens but nothing shows up.

I attach the GH definition.

Thanks in advance.