Why am I receiving the error "Unable to cast string to int64" and what does it mean?

I am trying to make a server-side music system, but MarketplaceService doesn't properly work.

Script:

game.ReplicatedStorage.MusicSystem.NewSong.OnClientEvent:Connect(function(music)
	progres.Size = UDim2.new(0,0,1,0) 
	local song = game.Workspace.SoundSystem.Music.SoundId
	local asset = game.MarketplaceService:GetProductInfo(song) -- This is the line the Error is on.

	songName.Text = asset.Name
	progres:TweenSize(UDim2.new(1,0,1,0),'Out','Linear',(song.TimeLength)-1)
end)

Error: Unable to cast string to int64

Sometimes the error doesn't show up at all.

local asset = game.MarketplaceService:GetProductInfo(tonumber(song), Enum.InfoType.Asset) 

Try this, your SoundId may be returning a string. I believe you also need to declare an InfoType, AKA GamePass, Dev Product, etc.

https://developer.roblox.com/en-us/api-reference/function/MarketplaceService/GetProductInfo source ^