Improving weka random forest

I am using weka classification...i interfaced weka with netbeans and m using NASA datasets of arff files PC1 data...In weka tool i observed that random forest gives better accuracy but stil i want to improve random forest accuracy so i just incorporated cfs with random forest which selects optimal features and passes to random forest to give better accuracy...now the problem is am getting no errors but still it doesn't shows any changes in accuracy or anything...please help me give some ideas in which the code and algorithm can change its performance