Can UP3/E function on slow speed with SCS?

I have installed a Speed Control System together with my UP3/E pump. Normal speed, pump is working perfect. When I select slow speed, the pump is pumping slowly for a while until it stops completely and it will not pump again until I press reset button. LED is steady red as from the moment I select low speed. When pumping the red and blue led blinks alternatively. When I select the high speed again, the pump is working perfect again. My question: Does someone recognize what I wrote down? Is the SCS compatible with the UP3/E or is it maybe not?