As much as we all like favourite formations any formation can beat any formation! there is NO ONE guarantee formation!!!!, there are so many variables in each game that go towards how the game sever predicts results so if like RJSlow, you are are not getting the required results then its time to look at your squad, key areas, check the stats of the players to see who is under performing, you may need to rest some players!, you may need to change some!, try starting with a different formation then go back to 4-5-1!, Are you rotating your squad?, even when I used to have a full 22 man 50T team I still could not win the treble every season!, so ask yourself, am I playing the same team to much?. am I over training them?, are they getting to old?, am I giving them enough booster packs etc!.
Make a record of say 10-15 games ofYOUR TEAM, what you played and the orders you chose and those of the OPPOSING TEAM!, eventually you will get a rough guide as to what you need to change to play against any given formation.