the external rnahello

[-= JB =-]

I am trying to write and external using XCode by following the  
instructions
in the Rev newsletter which shows how to create the external rnahello.

I have done everything it said to do but when I Build the external I  
get the
error:

error: There is no SDK at specified SDKROOT_ppc path '/Developer/SDKs/ 
MacOSX10.2.8.sdk'

Does anyone know how to correct this error so I can Build the external?

thanks,
-=>JB<=-