Problems in compilation of Sample1 - Mailing list pgsql-interfaces

Hi everybody!,I am tryng to compile the Sample Program 1 that comes with
the programmer's guide of PostgreSQL documentation. I've copied the
developement librarys to /usr/lib and the include files to /usr/include.
When I type gcc -o sample1 sample1.c -lecpg -lpq the compiler tells me:

/usr/lib/libecpg.so:undefined reference to 'crypt'

can you help me about the meaning of this error message.

Thanks!