no problem, i will wait
@SteveJG After some changes, it works, one problem is that can't delete the last linestring for a new tracking, is there a method for this ?
Yes. One way to 'delete' isshown in this tutorial within the code example How to broadcast a GPS location and share the information on a map with others in real time..CloudDB , sorry, the required code is only in the aia; an image of the Blocks that could be used is not in the actual tutorial documentation.
A similar method is code like this:
LineStrings cannot be deleted with code or values nulled out because a LineString requires there always be two locations associated with it . A developer cannot simply set LineString1.Points to an empty string. The values in the existing LineString consequently need to be replaced. Either of these code examples use code that replace the LineString with the current coordinates of the LocationSensor. That effectively 'deletes' your previous track display and the coordinates in a List of coordinates of the tracks collected so far and lets you start tracking fresh. The code disables the LocationSensor and requires you reenable it when you start a subsequent track.
The second example assumes Marker1 is the origin and Marker2 is the destination.
Experiment and let us know what works for you. 
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thanks a lot for this all explanation!