Hello Gurinder
All the parameters you have taken are correct .Also one of examples from the optisystem samples having WDM-OFDm also worked well.For 10Gbps data rate you can enhance your system for more transmission distance by using EDFA amplifier.Can you attach your system file?You can increase laser power to some extent to get good results and do not forget to check constellation of the system.Generally the common problem in OFDM sample is to set the delay in OFDM demodulator.You have to putt the delay value correct and you will get BER 0 i.e error free for 100Km distance.It would be better to if you attach file and we check your system file to correct any parameters in file.
Thank you