Maybe your yeast is old? Or the house isn't as warm as the other times when it rose better?

I poured some stale sesame oil into the ground today (where my former compost pile area used to be) after reading that was an acceptable way to dispose of vegetable oil. It was cold-pressed. I ought to have at least kept it in the fridge. Luckily my toasted sesame oil is still good; I used it in a dish yesterday that turned out quite tasty.