How do I pass in 2 parameters to a SSRS report, that's based on a SQL function query?

I'm trying to design a report based on a function query in our ERP. (as in, under Database/Programmability/Functions/Table-valued Functions)

The FROM clause is this:

FROM p21_fnt_invoice_hdr('COMPNAME', @ls_begin_invoice_no,@ls_end_invoice_no, 0, 9999, '0', 'ZZZZZZZZZZ', 0, 999999999, ' ', 'ZZZZZZZZZZ', ' ', 'ZZZZZ', 0,999999999, {ts '1900-01-01 00:00:00.000'}, {ts '2019-12-05 23:59:59.000'}, 'Y', 'N', 'N','B','Y', 'N','','N')

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If I run this in SSMS, providing the two parameters (@ls_begin_invoice_no  and  @ls_end_invoice_no),  it returns the data as expected.

But, I cannot figure out how to make SSRS work?

I get no results if I try & apply parameters..
No errors, just no results

thanks,

Rich