I need assistance

I need assistance

I’m following a build for the lightning ranger. I have all skills and supports but one of the supports I can’t use on a skill even though the build says I can. Deceleration on Cast on Shock. I have enough dex etc. But that support doesn’t support that skill. I’m on Xbox if that matters. But it frustrating cause that’s the only one left I need. I’m level 87 and broke and can’t do no dang t14-15 maps. Even have trouble with 13 sometimes. I’m new to POE and I have a lot to learn. But it’s hard to learn as I’m a stay at home dad with 4 kids 13 and younger. I just need some insight on this issue if there is any. Thank you.