[Tinyos-help] Problem with 'make pc'

[Roberto]

Hi all
I have a problem when i compile using make pc
I can see the following message:
---
penguin at laptop:/opt/tinyos-2.x/apps/Blink$ make pc
/opt/tinyos-2.x/support/make/Makerules:168: *** 

Usage:  make <target> <extras>
        make <target> help

        Valid targets: all clean eyesIFX eyesIFXv1 eyesIFXv2 intelmote2
mica2 mica2dot micaz null telos telosa telosb tinynode tmote
        Valid extras: docs ident_flags nowiring sim sim-fast tos_image
verbose wiring

Welcome to the TinyOS make system!

You must specify one of the valid targets and possibly some combination
of
the extra options.  Many targets have custom extras and extended help,
so be
sure to try "make <target> help" to learn of all the available features.

Global extras:

   docs    : compile additional nescdoc documentation
   tinysec : compile with TinySec secure communication

ERROR, "pc tos-ident-flags tos_image" does not specify a valid target.
Stop.
penguin at laptop:/opt/tinyos-2.x/apps/Blink$ make pc
/opt/tinyos-2.x/support/make/Makerules:168: *** 

Usage:  make <target> <extras>
        make <target> help

        Valid targets: all clean eyesIFX eyesIFXv1 eyesIFXv2 intelmote2
mica2 mica2dot micaz null telos telosa telosb tinynode tmote
        Valid extras: docs ident_flags nowiring sim sim-fast tos_image
verbose wiring

Welcome to the TinyOS make system!

You must specify one of the valid targets and possibly some combination
of
the extra options.  Many targets have custom extras and extended help,
so be
sure to try "make <target> help" to learn of all the available features.

Global extras:

   docs    : compile additional nescdoc documentation
   tinysec : compile with TinySec secure communication

ERROR, "pc tos-ident-flags tos_image" does not specify a valid target.
Stop.
penguin at laptop:/opt/tinyos-2.x/apps/Blink$ 
---

How can I solve this problem?
Thank you so much

Roberto