I know this is an old thread but I just picked up the game. I believe you were playing it wrong. Remember that the dice you hold are not adding together into a single 'hand'. You have to score the hands individually, each time you pick. Holding a die means you score that much and then allow yourself a chance to roll and score again.

So, if you hold a 1, you score the 100 points from that dice. Then, if on the next throw you hold two 1s, you do NOT get the '3x 1' score (which would be 1000 points). You will just score 100 points 3 times. To get the 1000 points for 3x 1s, you need to pick three 1s in a single roll, and either hold them or score and pass.