coverage.py problem

[Orin]

Hi,
I have a problem in using coverage.py module in my project:

./cov -c
Traceback (most recent call last):
File "./cov", line 10, in ?
coverage.the_coverage.command_line(sys.argv[1:])
 File "/usr/lib/python2.4/site-packages/coverage.py", line 363, in
command_line    self.collect()
 File "/usr/lib/python2.4/site-packages/coverage.py", line 467, in
collect
for file in os.listdir(cache_dir):
OSError: [Errno 2] No such file or directory: ''

The make file, in which coverage.py are been used is:
................
pythonpath=..
# Targets
.PHONY: pylint build test clean coverage
pylint: test
	$(MAKE) -C .. pylint
test: build clean_coverage $(test_results) coverage
coverage:
	./cov -c
	./cov -r -m ../src*py
build:
	$(MAKE) -C ../src
clean_coverage:
	-rm .coverage*
	./cov -e
clean:
	-rm *~* $(test_results)
# Tests
%.pass :: %.py $(srcs)
	-rm $@
	PYTHONPATH=$(pythonpath) DJANGO_SETTINGS_MODULE=$(settings) ./cov -x -
p $< && touch $@
...................
If anybody knows what can be the reason of this error, please tell me

With best regards, Orin