Help with mag card readers

writecard = function(fname,uname,pass)
magreader.beginWrite(uname.." "..pass, fname)
print("Hello World")
while true do
event = os.pullEvent()
if event == "mag_write_done" then
break
end
end
end

When ever this function gets used "Hello world" gets printed but the yellow light on the reader/writer doesn't come on and using a card on it doesn't write. It just gets stuck at the loop because a card isn't able to be written.

Yes I have set a mag card reader/writer peripheral to "magreader".
Yes I give valid strings for "uname" "pass" and "fname".

magreader.beginWrite("test", "test")
while true do
event = os.pullEvent()
if event == "mag_write_done" then
break
end
end

This part works when it's alone though.

Sorry for the bad code formatting, I'm not sure how to embed code onto fourm posts.

try executing the begin write in the lua prompt and see what it says, I have no clue what you are doing but that generally helps, perhaps your arguments are incorrect

the function is fine, try restarting minecraft. If that doesn't fix it, something is wrong somewhere else in the program containing this.

I was using rednet to get the variables. And apparently I set the variables to the sender's ID and not the message. So I didn't have valid strings, I tried to give it numbers. >.<

Thanks for the replies.