COUNTIFF function returning a zero

Hi there, 

I'm new to complex formulas (!) and looking to create a COUNTIF to track the number of leads from a variety of sources* within a date range.  The sources are in a drop down list and I would like the date range to be easily adjusted to give a monthly result (this is my D6 for start date and F6 for end date)

My 1st argument is B13:B101 for the source eg website

2nd argument is C13:C101 for the date of the enquiry

My formula looks like this:

=COUNTIFS($B13:$B101,B111,$C13:$C101,">="&$D6,$C13:$C101,"<="&$F6)

I want the outcomes to appear in a table where I can track number of leads from website, social media etc in a given range for one of my clients but the value is coming out as zero.

I have changed the date format to year,month,day with the year as 4 digits but still no joy.  Any advice would be massively appreciated!

Thanks so much 🙂

Jo