Dear @saeed_badali
may I add some other comments:
in your Screen1Initialize block you try to connect the BT before having granted it the permission and in the PermissionGranted event you ask again for the permission.
Maybe I'm missing something ?

I guess that you shall remove the Connection block from the Initialization, and move it in the Permission granted in place of the second "asking":
Someting like:
Then, in the "if then else" sequence of Orientation Changed block, there is an else that (if I have correctly understood) is never reached:

In my understanding the 1st "if" checks for a value outside the limits -30 and + 30
then if the value is outside, you check wheter it is greater than 30: if yes you send something,
if not you check if less than - 30; and if less than -30 you send something.
If not you send 140. But this last case should never happen since the first "if" checks for outside the limits -30 and + 30.
A the end if the value is, on the contrary, within the limits (i.e. between - 30 and + 30) you send 140.
Then to make it simpler you should consider something like:
This does not solve your BT problem, but it helps in doing things easier.
Another hint is to verify whether the app is really sending out data on the BT.
To this purpose I suggest you to try with a terminal program like TeraTerm on your PC. This very simple tool (free) allows you to find the BT sender source (your phone running the app) and to show whatever arrives to the PC on that line (the BT are typically seen in the Serial Lines list, as one of the COM's).
So, to make one step at a time, reduce your app to a very few rows, i.e. just open the BT client, connect it and send a "Hello World" to Tera Term. When you are done with it, then you can enrich your app by sending the effective data you want.
Best wishes !
PS last but not least : please be aware that for newer Android, in order to allow the BT transmission, it is necessary to set at Android level, the permissions to your app and for some mysterious reason, also the geo-localization. Give it a look, there is plenty of other topics on this matter in the Community.