Water escaping through backwash hose

[irishsph]

Recently replaced by lateral assembly valve in my Hayward sand filter. Now when I turn on my filter i have a small stream of water that constantly escapes thru my backwash hose.
I must have done something wrong installing the new lateral assembly, no?
Oh, AND i still have some sand and dirt recirculating back into my pool. Not a happy pool owner right now.
Short of calling a professional, not sure what to do.
Help!

Thanks.