cygwin lcov genhtml: ERROR: cannot create directory ?

I am executing the following command, which is resulting in the error below. I have chmod 777 to all directories involved. The css and image files are written successfully, but the html file(s) is not getting generated. What a开发者_运维问答m I do worng?

perl genhtml -o coverage jsTestDriver.conf-coverage.dat

Reading data file jsTestDriver.conf-coverage.dat
Found 4 entries.
No common filename prefix found!
Writing .css and .png files.
Generating output.
mkdir: cannot create directory '': No such file or directory
genhtml: ERROR: cannot create directory !

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