How do I fix this error?

I already got this answered, but all of a sudden there was an error that popped up. Here is what I have:

Script:

local bin = script.Parent
local decal = bin.Decal

local MainSlides = {"http://www.roblox.com/asset/?id=154539172", "http://www.roblox.com/asset/?id=177042272",
"http://www.roblox.com/asset/?id=157119414", "http://www.roblox.com/asset/?id=175271294",
"http://www.roblox.com/asset/?id=198632478"}

local SoundsForSlides = {12222030} -- Add more if you wish, will play with the slide

local function runTable(table, delayTime)
    for i=1,#table do
        decal.Texture = table[i]
        wait(math.random(2, 5)) --The time can vary from 2 to 5 seconds.
        if SoundsForSlides[i] then
            SoundsForSlides[i]:Play() --If this doesn't work tell me
        end
    end
end

while wait() do
    runTable(MainSlides, WaitTime)
end

Error

20:30:45.135 - Workspace.Part.SlideScript:15: attempt to index field '?' (a number value)

SoundsForSlides is a Number Value, not the actual Audio, but, your attempting to play a Number Value, that is the problem on line 15, however, this can be fixed, by using/creating a Sound type instance, and by setting the SoundId property to the Number Value, let me explain;

local SoundId = 175215264 --'SoundId' is identifying the Number Value '175215264'

local Sound = Instance.new("Sound",game.Workspace) --Identifier 'Sound' is now identifying/specifying the create 'Sound' type instance, and sets it's 'Parent' to 'game.Workspace'
Sound.SoundId = "http://www.roblox.com/asset/?id="..SoundId --This sets identifier 'Sound''s SoundId property to identifier 'SoundId''s Number Value, I added the link because IT IS required, as well as, I have seen it is not require to, but I simply do not trust it, otherwise, failing to add the link, it WILL NOT play, and will result in an error, and saying the Audio does not exist
Sound:Play() --This will play identifier 'Sound' in the Workspace 'Globally'

Hope this helped!

With the'SoundsForSlides' table, you just have an index with an int in it. Then on line 15 when you attempt to index SoundForSlides[i] and use the Play() method on it.. The Play method is a method of the Sound object, not numbers. That's like saying 12222030:Play().

Create a sound object with the SoundId as SoundsForSlides[i]'s id.

local bin = script.Parent
local decal = bin.Decal

local MainSlides = {
"http://www.roblox.com/asset/?id=154539172", 
"http://www.roblox.com/asset/?id=177042272",
"http://www.roblox.com/asset/?id=157119414", 
"http://www.roblox.com/asset/?id=175271294",
"http://www.roblox.com/asset/?id=198632478"
}

local SoundsForSlides = {12222030} -- Add more if you wish, will play with the slide

function playAudio(ID)
	local s = Instance.new('Sound',bin)
	s.SoundId = "http://www.roblox.com/asset/?id="..tostring(ID)
	s:Play()
end

function runTable(table, delayTime)
	for i=1,#table do
		decal.Texture = table[i]
		wait(math.random(2, 5))
		if SoundsForSlides[i] then
			playAudio(SoundsForSlides[i])
		end
	end
end

while wait() do
	runTable(MainSlides, WaitTime)
end