WTTlog system datetime

I make a PHP script which parse a xml file created with WTTlog.

My problem is when i want to take datetime from xml, it's only one time at start of file, and no more in rest o file, but when i open that log with DTM, i can see time for everyline.

 <RTI ID="3738445142" BaseTime="2015:1:15 18:31:25:200" Frequency="14318180" /> 

and for everymessage that BaseTime doesn't appear or some time, it's look like:

<Msg UserText="Test Done." CA="826116213" LA="826116900">
   <rti id="3738445142" /> 
   <ctx id="384048256" /> 
</Msg>

Knows anyone how i can get time for every info ?

Thanks!