help with logs.

This is only happening to one number I call or message. My troubled 15 year old. My calls show up on my log yet not one of my text do from a second phone they have. So if I text two messages back to back to two different numbers from my phone the log will either never show the second line or will show my line twice. Why? And at this time apples IM is not on either device just using the regular text messages.