Betta breeding help!! Male bettas won't make bubble nest?

I have 13 bettas and am currently trying to breed 10 of them. I got them all from the pet store :( (since theyre usually old) and 1 of the males I know is 1 year old plus whatever age I got him at. The others are all fairly new. I paired the 10 off and put the girls in a see through cup in a tank. ( each pair has their own tank) I am wondering why the males won't make bubble nests. I am feeding them live food and all five girls have a white dot and all the dark ones have vertical not horizontal stripes. The problem is non of the males are making a bubble nest. I have the temp at 81-82 too. Please help