I've made 3 wines this autumn. Blackberry, elderberry and sloe. The blackberry fermented OK but the other 2 stopped short, one at 1.020 and the other at 1.060 from a starting sg of about 1.090. All were fermented in the same temp controlled chest which maintains a must temp of 20 degs C. I've made these wines in previous years to the same formulation with no problems. Any suggestions?