If you cannot transmit, the two most likely issues are 1) Microphone and 2) Sub channels.
To troubleshoot the microphone problem, try to use an external headset or speakermic. If that transmits with the headset but not without, then your built-in microphone is shot. If it still does not work, then check CTCSS/Sub Channels.
Sub channels are evil and should never be used. At least that is my opinion. If they are using sub-channels, then check to see if THEIR sub-channels (referred to as CTCSS) are off on theirs. They should be on channel 1 sub-channel 0, for example, and you should be on 462.5625 MHz with no CTCSS for transmit or receive.
The software requires a programming cable but they are really cheap:
USB: $8.50 USD
http://www.409shop.com/409shop_product.php?id=103760
Serial: $8.00 USD
http://www.409shop.com/409shop_product.php?id=103756
If BOTH above do not work then the transmit circuit may be the problem.