Sketch will no upload to Arduino Zero

Computer: IMAC.
OS: OSX 10.11.1
Arduino Software: 1.6.6.
Arduino Zero library installed.
Computer connected to programming port.

When I "verify", I get the following:

Warning: platform.txt from core 'Arduino SAMD (32-bits ARM Cortex-M0+) Boards' contains deprecated recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{build.path}/{archive_file}" "{object_file}", automatically converted to recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{archive_file_path}" "{object_file}". Consider upgrading this core.

Sketch uses 12,132 bytes (4%) of program storage space. Maximum is 262,144 bytes.

When I try to "Upload", I get the following:

Warning: platform.txt from core 'Arduino SAMD (32-bits ARM Cortex-M0+) Boards' contains deprecated recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{build.path}/{archive_file}" "{object_file}", automatically converted to recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{archive_file_path}" "{object_file}". Consider upgrading this core.

Sketch uses 12,132 bytes (4%) of program storage space. Maximum is 262,144 bytes.
Open On-Chip Debugger 0.9.0-gd4b7679 (2015-06-10-19:16)
Licensed under GNU GPL v2
For bug reports, read
http://openocd.org/doc/doxygen/bugs.html
debug_level: 0
adapter speed: 500 kHz
adapter_nsrst_delay: 100
cortex_m reset_config sysresetreq
target state: halted
target halted due to debug-request, current mode: Thread
xPSR: 0x41000000 pc: 0x00000858 msp: 0x200023a0
** Programming Started **
auto erase enabled
wrote 24576 bytes from file /var/folders/kk/lh14v8t17hlbv2rzn3td68d80000gn/T/build9a6367f71b11745f710c22a196901664.tmp/AnalogReadSerialPWM.ino.bin in 2.953658s (8.126 KiB/s)
** Programming Finished **
** Verify Started **
verified 12316 bytes in 1.027062s (11.710 KiB/s)
** Verified OK **
** Resetting Target **
shutdown command invoked

I following the "Getting Started" with Arduino Zero instructions.

AJJ1:
** Programming Started **
[...]
** Programming Finished **
** Verify Started **
[...]
** Verified OK **
** Resetting Target **
[...]

that shows IMHO that everything worked well and programming is done.

the "Warning: platform.txt ... blah" message is a "normal behaviour" with the 1.6.6 IDE,
only a warning, you don't have to care about...

Dirk67,

Thanks. I tried the "Blink" sketch and it works fine.

AJJ1