i'm still learning Haskell and need help with the type inference please!

using packages SDL and Yampa i get the following type signature from FRP.Yampa.reactimate:

(Bool -> IO (DTime, Maybe a))

and i want to use it for:

myInput :: Bool -> IO (DTime, Maybe [SDL.Event])
myInput isBlocking = do
    event <- SDL.pollEvent
    return (1, Just [event])
...
reactimate myInit myInput myOutput mySF

but it says

Couldn't match expected type `()'
       against inferred type `[SDL.Event]'
  Expected type: IO (DTime, Maybe ())
  Inferred type: IO (DTime, Maybe [SDL.Event])
In the second argument of `reactimate', namely `input'
In the expression: reactimate initialize input output process

i thought "Maybe a" allows me to use anything, even a SDL.Event list? why is it expecting "Maybe ()" when the type signature is actually "Maybe a"? why does it want an empty tuple, or a function taking no arguments, or what is () supposed to be?