arduino only seems to receive zeroes

arduino only seems to receive zeroes

I have effectively created a portable serial terminal using an LCD and an
arduino uno (as part of a wider project) when there is no data being sent
to it it just prints no data (as programmed) however when it receives data
it clears the screen and prints the data, well that's the idea any way it
just displayed 0 when ever i sent it anything so then i changed the
program so that it sent the data it received back to the computer and it
just sent zeroes. i have tested it with a separate FTDI bored and
monitored it with a different terminal (termite) the same happened then i
tried a different computer and the same happened again. i connected the rx
and tx lines to the arduino xbee shield and got the arduino to chuck some
numbers at it and i monitored the out put using the picaxe connect bored
and it was receiving what the arduino was sending however when i sent data
to it it just displayed zeroes again. if any body knows what the problem
is pleas help.