Having trouble with postie

using postie. examples of code

client

local function func()
  local result = postie.SignalServal("event", {data = data})

if result then
do whatever
end
end

server


local function onSignalFunction(player, data)
if whatever then
return true
else
return false
end

postie.ListenSignal("event", onSignalFunction)

it returns randomly true sometimes when is supposed to be false but most the time returns false, especially when supposed to be true.