Problem with the threadsafe programm.

Hello, I am doing a work experience at Opteway and I am following your work about time zone. I am also working about the threadsafe version and I noticed some problems. The problem : when I use the "tz_prep" function of the library "libtz.a", it indicates me an error. This function works correctly on Linux but doesn't work neither on SunOS nor on Tru64. Thank you for your attention.