Motorola SX600 Triuble shoot ?

I have an older set of these radios, I have them both set to same channel and interference eliminator code but they won?t transmit to each other, or at least i can?t hear anything coming across. Any suggestions?

Update: I did some digging around the forum and found a similar issue, I learned that even though the battery indicator shows fully charged, the batteries may be old and not able to generate the power required to transmit. I replaced the original battery packs with AAA batteries and all is good now. Thanks.