Your English is quite adequate, even though I don't know what a boxe captor is. Your problem is far from clear, but that has nothing to do with language. What you need to be absolutely clear about in this particular forum thread is which version of PLX you are trying to use, and which version of Excel. This particularly applies here because the last version of Excel that the original PLX reliably works with is in Office 2003 and therefore probably older than you are. So, where are we with that?
IF you are using PLXv2, I suggest you take the problem to that forum, linked to in reply #1. IF you are using the original version from Parallax AND NOT using Office 2003 or older, I suggest you cease doing so and get v2, same link.
Either way, I suggest you studiously refrain from reading reply#2. That 12volt guy is either guessing wrong, or lying, or is very lucky, or is very, very smart.
Now, that I have looked at your code, it seems reasonably kosher, apart from the complete lack of any timing control. The speed of the loop is governed by the amount of data and the ability of Arduino to communicate it. Maybe this is your intention, I recognise that the occurence of the events may not be regular, but it is probably bad practice, and you may be presenting Excel with a mess it cannot handle.
If you put a
in the loop is may work sensibly.