HI Ashish Khemka,nnPlease can you explain me a little more your answer because I didn't understand it well,nnMoreover I want to inform you that when I effected the nonlinear transient analysis with positive acceleration values it works fine but when I used negative acceleration values it displays directly to me the same error message nnI don't know now if I can't apply negative acceleration values to INFIN257 or if there is something that needs to be settle to allow me to do this analysis.nI appreciate your help,nRegards,n