lcov genhtml 'no data found' issue - profiling

Question

I am using the latest version of lcov downloaded from here http://ltp.sourceforge.net/coverage/lcov.php on Windows 10. I am able to generate .gcda, .gcno, and .info files that appear valid. Also, when I run gcov, it outputs a valid .gcov file. However, when I run genhtml on the .info file, I get the following output:
C:\Users\Yuxin Zhou\Documents\work\gcov_test>genhtml.pl coverage.info
Reading data file coverage.info
Found 1 entries.
No common filename prefix found!
Writing .css and .png files.
Generating output.
Writing directory view page.
Overall coverage rate:
lines......: no data found
functions..: no data found
Here is my batch file:
gcc -O0 --coverage test.c -o test.exe
test.exe
gcov test.c
lcov.pl -o coverage.info -c -d "C:\Users\Nick\Documents\work\gcov_test"
genhtml.pl coverage.info --output-directory html
Here's the output from gcov:
-: 0:Source:test.c
-: 0:Graph:test.gcno
-: 0:Data:test.gcda
-: 0:Runs:1
-: 0:Programs:1
-: 1:#include <stdio.h>
-: 2:
1: 3:int happy_now(int x)
-: 4:{
1: 5: return x + 2;
-: 6:}
-: 7:
1: 8:int main()
-: 9:{
1: 10: int x = happy_now(3);
-: 11:
1: 12: if(x == 0)
-: 13: {
#####: 14: printf("hello world\n");
-: 15: }
-: 16: else
-: 17: {
1: 18: printf("goodbye world\n");
-: 19: }
-: 20:}
Why do I get
Overall coverage rate:
lines......: no data found
functions..: no data found
?