Request failed with clothing?

I made a script that stores your character's clothes and applies them back to your character if you speak the phrase "/clothes." However, when I do this, I get the error Image failed to load Workspace.Player1.Humanoid Clothes : http://www.roblox.com/asset?id= because Request failed and the Shirt/PantsTemplate of the clothing just shows the 'prefix.' Here is the script:

local Prefix="http://www.roblox.com/asset?id="

game.Workspace.ChildAdded:connect(function(char)
    if char:FindFirstChild("Humanoid") then
        local p = game.Players:FindFirstChild(char.Name)
        if p then
            if char:FindFirstChild("Shirt") then
                sh = char.Shirt.ShirtTemplate:sub(31)
            else
                local d = Instance.new("Shirt")
                d.Parent = char
                d.Name = "Shirt"
                sh = d.ShirtTemplate
            end
            if char:FindFirstChild("Pants") then
                pa = char.Pants.PantsTemplate:sub(31)
            else
                local d = Instance.new("Pants")
                d.Parent = char
                d.Name = "Pants"
                pa = d.PantsTemplate
            end
        end
    end
end)

function onChatted(msg, recipient, speaker) 
msg = string.lower(msg) 

if (msg:lower() == "/clothes") then 
speaker.Character.Pants.PantsTemplate = Prefix..tostring(pa)
speaker.Character.Shirt.ShirtTemplate = Prefix..tostring(sh)
end 

end 

function onPlayerEntered(newPlayer) 
newPlayer.Chatted:connect(function(msg, recipient) onChatted(msg, recipient, newPlayer) end) 
end 

game.Players.ChildAdded:connect(onPlayerEntered) 

Please help.