Help with Vanilla Bridge

I have beem reading up on and watching tutorials on Vanilla bridges. This is something specific that I would like to incorporate into Slipgate.wad (a D2 remake of Quake e1m1.I'm so effing close to getting it that I can taste it. Can someone here please explain to me exactly where I am going wrong? My bridge works totally fin until I put cross beam in it. Then it gets all weird and glitchy. Now I have it functional, but it does weird things with the texture and rendering bleed.