Rikoooo MD-88 twin pack ils question

[riverbedjedd]

Hello,
Im new to this forum and i would appreciate any help with my issue. I am flying the MD-88 twin pack by rikoooo, my favorite plane by the way. Im having a problem when doing an ils landing. I capture the localizer, and then i capture the glide slope fine except the md-88 will not automatically start descending like with all the other planes and default fsx planes i have flown. i figured out there is no app button on this plane it is an AP ils button which was confusing at first. Can anybody tell me what im missing or doing wrong?? is there something extra i have to do with this plane after i catch the glide slope, i do fly with FDC so it lets me know when the glide slope is captured
Thanks everyone any help would be much appreciated,