Why can't I get the DataStore values of this id?

I'm trying to make an ingame friend system, and it's sadly not working. I'm trying to use this bit of code to update the friends datastore to say that I'm offline.. And playerData always gets nil.

function DataStore:UpdateStatus(player, isOnline)
    for i = 1, #sessionData[player] do
        local friendID = game.Players:GetUserIdFromNameAsync(sessionData[player][i]["Name"])
        if friendID ~= nil then
            output(player, ":", friendID)
        end

        local playerData = FriendData:GetAsync(friendID)

        output("DEBUG", playerData, #playerData)

        if playerData ~= nil then
            for i2 = 1, #playerData do
                for i3 = 1, #playerData[i2] do
                    if playerData[i2][i3]["Name"] == player.Name then
                        playerData[i2][i3]["Online"] = isOnline
                    end
                end
            end

            for a = 1, #playerData do
                for b = 1, #playerData[a] do
                    output("DEBUG", a, b)
                end
            end

            FriendData:SetAsync(game.Players:GetUserIdFromNameAsync(sessionData[player][i]["Name"], playerData))
        end
    end
end