first, make sure your assembler is active and powered. if you see a lil laoding bar at the bottom constantly filling up and resetting once full then its active and attempting to craft items.
then make sure you selected what it is you would like to craft from the filter menu.
then finally add the appropriate materials as indicated in the graph tab to have your item crafted.
And lastly but most importantly. glass sub blocks (wedges, corners, ECT) currently have no recipes. so they cannot yet be crafted. neither can any of the FTL blocks (jump drives and warp gates) however all those should be coming soon! (or you can buy them from the shop if you really want them, depends on how hardcore you want your survival play to be) for now i am just sticking to regular full sized blocks of glass, those are craft able and will have to do for the mean time. and you might wanna lower their recipes cuz they are a bit expensive ATM. i lowered it to 16 rather then 120.