linking problem... file not recognized: File format not recognized

[fantasticamir]

I have a simple program using a couple of classes and it compiled successfully but while it is linking I have the following problem:

g++ -Wall -lcu -lglu ACL2MDD.o Link.o Rule.o reachability.o -o Reachability
Link.o: file not recognized: File format not recognized
collect2: ld returned 1 exit status
make: *** [Reachability] Error 1

Another observation is the Link.o and Rule.o files, both of them are HUGE (20 MB) which is odd because the classes are so small.

The following is my make file:

# Compiler/Linker
CC = g++
LD = g++

# files removal
RM = /bin/rm -f

CFLAGS = -Wall
LDFLAGS = -Wall

MDDLIBS= -lcu -lglu

# program's object files
PROG_OBJS =  ACL2MDD.o Link.o Rule.o reachability.o 

# program's executable
PROG = Reachability

# top-level rule
all: $(PROG)

$(PROG): $(PROG_OBJS)
	$(LD) $(LDFLAGS) $(MDDLIBS) $(PROG_OBJS)  -o $(PROG)


Rule.o:  Rule.h
	$(CC) $(CFLAGS) $(MDDLIBS) -c Rule.h -o Rule.o

ACL2MDD.o: ACL2MDD.cpp ACL2MDD.h
	$(CC) $(CFLAGS)  $(MDDLIBS) -c ACL2MDD.cpp -o ACL2MDD.o 

Link.o:  Link.h
	$(CC) $(CFLAGS)  -c Link.h -o Link.o
reachability.o:  reachability.cpp ACL2MDD.cpp ACL2MDD.h
	$(CC) $(CFLAGS)   $(MDDLIBS) -c reachability.cpp -o reachability.o


# clean everything
clean:
	$(RM) $(PROG_OBJS) $(PROG)

Any idea?
Thanks for your help in advance...

Amir.