Speech recognition

[osama]

i am using pocketsphinx for speech recognition to move turtlebot. but my words are not recognized correctly except one word or two? can anybody help me how can i recognize correctly only four words forward backward, left, right. i have used many other packages as well, and also read how to make my own language model as mentioned in cmusphinx but i cannot understand the steps i should follow. what should i do to recognize only four words by pocketsphinx