simple math and long time coming

first off let me ask, has anyone had trouble with Simple Math conception? I bred 4 different cows to him last year multiple times and resulted in zero calves. I went 67% on the rest of my herd and 18 cows for other people so I ruled out that it was me, considering i bred them multiple times you wouldve thought 1 wouldve caught. Anyhow, how has everyone liked their simple math calves? and has anyone liked their long time coming calves? I saw a video of him and loved how he looked for a maternal bull. I am wanting to flush a cow of ours thats old school bred to make females and want to use one of these bulls. Thanks for any input on my 3 questions!

I had trouble with Simple Math the first time i flushed my donor cow, ended up with no good embryos. However, i used my last 2 doses to breed a pb sim cow that was wasty fronted and cow legged. Got a heifer out of her that is nice, she was pretty big footed 100lb calf that had to be pulled. Shes 2 months old now and clean fronted, stout and sound. The only problem i am having is i cant register the halfblood heifer because Simple Math hasn't  been approved as an AI sire with the ASA and it would cost $200 plus a dose of semen to register her. I like him but probably won't use him again since I can't register calves out of him.

bump

We bred 4 head to Simple Math a few years back, none of them took. Bred them to different bulls the next heat cycle and they all took. We have since purchased 2 bred heifers sired by him and they've made great cows. Always calve easy, milk well and wean big calves.