Need help from a newby

My declaration is as followed:-

type Address = Int
data Port = C | D deriving(Eq,Show)
data Payload = UP[Char] | RTDP(Address,Port) deriving(Eq,Show)
data Pkgtype = RTD | U deriving(Eq,Show)
type Pkg = (Pkgtype,Address,Payload)
type Table = [(Address,Port)]


findport::[Pkg]->[Table]->[([Pkg],[Pkg])]
findport [(pt,ad,pa)]  [(a,p)]
      | ( p == C) = ([pt,ad,a],[])
      | otherwise = ([],[pt,ad,a])

Error received:-

Type error in explicitly typed binding
*** Term           : [(a,p)]
*** Type           : [(a,b)]
*** Does not match : [Table]

Can anyone please help?