Hi Hung, Are you using laptop's trackpad or separate mouse? Do you try to rotate the model directly from 3D or using the onscreen buttons? Is the model viewed in fullscreen mode in the external monitor? Do you see some events logged? (open Event viewer, browse to Applications and Services Logs / Tekla, if there are something that could explain this, please save the events to a file and send it to admin@teklabimsight.com) Best regards, Marko Myllymaa