Give it morning sun or afternoon sun. In its natural habitat it is in rainforest in the shade or high shade and lots of humidity.
"The habitats of this cacti specie considered epiphytes, these plants grow on other plants, sides of trees or in branch forks."
I have mine in a few hours of morning sun and a few hours of afternoon sun. You will not get the results you want if you stress it with to much sun. I do half fertilizer all Summer with each water. Water very little in the winter. About once a month it gets a drink. My red one blooms in March and the white one blooms in August.