In my last game despite having the throw, I lost all my linouts. My 2nd rows were comparable if not better than my opponents. The only difference was I was playing away from home. Any ideas?
Why do I lose so many lineouts
To perform well, your lineout target has to have a high Lineout jump stat, and the players either side of him have to have good Lineout strength. Also, your hooker has to have high Pass accuracy. Any of that falls down in comparison with your opponent, and you will lose lineouts.
You'll find it's one of the first parts of your games that goes to sh!t as your players tire, so fitness and rhythm play a part on top of the nuts and bolts that Waspy describes above.
You might also want to tinker with your "Pass Speed" on your hooker. "Accuracy" is more important but "Pass Speed" may be too high or too low. That plus everything else the guys above have said can all play a part.