Unexpected error on os.date() script for GUI, How to fix this error?

I am making a date GUI, but there's an error and I don't really know what it means and how to fix it. I would appreciate any help.

Error: " os.date's first argument must be either 't' or '!t' "

Error line: Line 2.

Script:

while true do
    script.Parent.Text = (os.date("Today is %A, %B, %x,", 906000490))
    wait(3600)
end