Raúl, I'm sorry for not responding sooner. I was traveling and missed this post. Let me try to reproduce this and I'll let you know what I find shortly.
Raúl, I tried this and did run into a snag that I think may be what you hit, but I did get this working. First, here's the data pattern I created:
Note: I did update the date in your sample log data to today's date and time. This doesn't affect anything, but just wanted to mention it.
As you can see, the data pattern did work just fine. Note that the Date Format dropdown (I have highlighted it in red) had to be set to the format that matches our date format - in this case that's dd/MM/yyyy HH:mm:ss.
After that, I created the file /tmp/raul.log on my test system and created a data collector as shown here:
As you can see, it read the sample content I put in the file by default, and matched that data with the "Raul" data pattern I created earlier.
I created the data collector and then added one new line to the file. In adding this line, I updated the time/date to the current time & date. ITDA did pick up that new entry as you can see in the collection history window here:
Can you try again and set your data pattern settings just as I show in these screenshots and let me know if that fixes your problem. Also, I would be very interested in knowing exactly what the problem was, so please let me know.