HELLO MUHAMMAD FARID..
Are you executing a sample osd file from the optissytem examples..? There error usually occurs when there is some logical error in the design.. You must be changing some parameter which you maybe doing wrong.. i suggest you to first run the osd file as it is.. and then make changes.. If the error still occurs then you can ask for help from the optiwave support.. I hope it will help.
Thanks & regards