It's Ti2Ni, which is in FD-3M spacegroup. I have its .cif file which can be loaded by many crystal building program. So I try to build the structure according to the loaded images. I started building a structure with FD-3M lattice. But when I tried to add atoms at the position read from the loaded structure (I click on the atoms of the loaded structure so it tells me the position of this atom in the lattice), in my own builder, the positions of the automatically added atoms (besides the one I added) are different from the loaded structures. For examples, I read there is a Ti atom at position (0.25, 0.75, 0.5) fractional coordinate. But if I add this one, there are some extra Ti atoms coming out, which is also wrong compared to the loaded structure. I successfully built some body centered cubic crystal structures (which is also easy) but not this one... I've uploaded its .cif file if someone can take a look at it.