LINE_INDEX with SORTED table returns value > 0, but SY-TABIX = 0

Hello everybody,

I'm using table function LINE_INDEX to find a specific row within an internal table of type sorted with non-unique key (table type LE_T_DLV_HD_ADR).

The problem is, that the function returns a value greater than 0 (in the following example 2), but SY-TABIX is set to 0.

This is my test example:

DATA ls_delnote TYPE ledlv_delnote.
DATA lv_index TYPE i.
ls_delnote-hd_adr = VALUE #( ( deliv_numb = '0000000001'                                                           partn_role = 'AG' )                                                         ( deliv_numb = '0000000001'                                                            partn_role = 'WE' ) ).
CLEAR sy-tabix.
lv_index = line_index( ls_delnote-hd_adr[ deliv_numb = '0000000001'                                                                            partn_role = 'WE' ] ).
IF line_index( ls_delnote-hd_adr[ deliv_numb = '0000000001'                                                             partn_role = 'WE' ] ) > 0.  WRITE: / 'LV_INDEX:', lv_index.  WRITE: / 'SY-TABIX:', sy-tabix.
ENDIF.

The result is:

LV_INDEX:         2

SY-TABIX:          0

Why SY-TABIX is set to 0? We are using release 7.40 EHP7.

Thanks

Daniel