Why doesn't tick() work with text?

I don't know why it doesn't work,and it running on a regular script. If you managed to fix it please explain how.

while true do
    wait(1)
--~--~--Varibles--~--~--~--~--
local ClientSeconds = tick()
Hour = math.floor(ClientSeconds/3600)
Minutes = math.floor(ClientSeconds/60%60)
Seconds = math.floor(ClientSeconds%60)
TimeGui = script.Parent
---------------------------------
TimeGui.Text = Hour..":"..Minutes
end