error in line 23, i have a string written out, but the output is claiming i dont?

I am trying to make an updating and saving datastore (obviously), and I can't seem to figure out why I'm getting an error on this code game.Players.PlayerRemoving:connect(function(plyr) child=plyr.bin:GetChildren() for i=1, #child do child[i].Value=ds:SetAsync("magicUser-"..plyr.userId..child[i].Name,child[i].Value) end end)

the error is:   18:24:24.320 Workspace.DataStore Global Leaderboard:23: invalid argument #3 (string expected, got nil)  -  Server  -  DataStore Global Leaderboard:23

thanks in advance for any help!