I work where we need two way radios i purchased used ones from ebay and took them to work and set them to the codes that the directions said. both the motorola xtn series and the cp100..older models. they can hear me..meaning it will transmit but i can not hear them. any suggestions to whats wrong

On the XTN and CP100 series radios you have 4-6 items which would need to be programmed: Frequency, Code, Scramble, Wideband/Narrowband, Mic Gain, and VOX. You can tell when you've reached the end of programming through the steps because the "chirp" will sound different.

Just a few thoughts which might help you:
1) Check to see these items match identically: frequency, code, scramble and wide/narrowband. (note: the numbering system on frequencies differs between the two models.)
2) If you are using an audio device and/or VOX, be sure you have the radio turned OFF when plugging in the device.
3) Check your mic hole to make certain you do not have debris or something covering the hole.

Educated guess you might have the code set differently between the radios. If these suggestions do not solve the problem, google our company name and give us a call, we can walk you through checking the programming over the phone. Have both a known good CP100 and XTN radio handy.

Best regards.