silvaco atlas error: during use of curvetrace statement for simulating thyristor.

[arvindmishra]

i am trying to simulate thyristor and for back snaping i m using curvetrace statement but i m getting error after the mincur value and error is

Warning: Solution algorithm cannot reduce residual(s).
Warning: Convergence problem. Take smaller
bias step.
Error: Tracer unable to project past last solution.
Error: Errors in projection during curve tracing.