Autonumber Paragraphs starting at zero

Hi all

(first time poster)

On a FM document, i need Heading 1 autonumber start at 0.

Created two paragraph style (assuing that is the best approach to do it)

 H1_Heading1 with autonumber H:<$chapnum>.<n+> 

 H1_Heading1_Begin with autonumber H:<$chapnum>.<n=0> 

but when try to define the header to show on each page the current "Heading 1" with Running H/F (<$paranum[H1_Heading1]>) it only starts, has expected, on the Chapnum.1 

there is any (simple) way to have the header working for the 0 also? 

many thanks