ERROR: program SAPSLDAPI_UNICODE not registered

I'm using the transaction SM59 and i make a test of the conection SAPSLDAPI and i get the following text:

EntrSist. Error de conexión

Det.error Error when opening an RFC connection

Det.error ERROR: program SAPSLDAPI_UNICODE not registered

Det.error LOCATION: SAP-Gateway on host serverxi.ejemplo.com / sapgw05

Det.error DETAIL: TP SAPSLDAPI_UNICODE not registered

Det.error COMPONENT: SAP-Gateway

Det.error COUNTER: 3705

Det.error MODULO: gwr3cpic.c

Det.error LINE: 1694

Det.error CÓD.RETORNO: 679

Det.error SUBRC: 0

Det.error RELEASE: 700

Det.error TMP.: Sat Aug 25 12:51:44 2007

Det.error VERSIÓN: 2

does anyone know what i have to do?

Thanks in advance...