after make html I got this:

Code:
g++ -I. -I../Sources/Core/.libs `pkg-config --cflags clanCore-2.1` -pthread reference_docs.o reference_all_classes.o reference_class.o reference_define.o reference_enum.o reference_function.o reference_grouped_classes.o reference_index.o reference_typedef.o -o ReferenceDocs `pkg-config --libs clanCore-2.1` -lpthread
/usr/bin/ld: cannot find -lclan21Core
collect2: ld returned 1 exit status
any hint how to resolve this?