We have noticed that Security Permission defaults are a bit troublesome depending on the carrier your BlackBerry uses and the OS level installed.

For troublefree operation, please double-check that your application permissions for REXconnect are set to allow:

1) Go to BlackBerry Options / Security / Application Permissions
2) Find REXconnect on the list
3) Edit Permisisons
4) Mark all three sections at the top to Allow
5) Save and Exit

This seems to be a consistent problem with BlackBerry 4.3 OS devices on Verizon and Sprint, but is probably a good idea across other carriers as well.

Thanks,

--the REXguys--

More Info about REXconnect for BlackBerry
REXwireless FAQ