Dump while using alv structre

Question

HI ALL,
i working on the with alv tree and i am calling to the following method
with structure SYST (just for test )and the problem is that i try to put my structure
i have a dump ,
i the alv tree i dont dispaly any table just one column with all
the needed data .
my structure have just one column type LVC_VALUE .
what i miss here i want to replace the structrue SYST with my structure?
mo_tree->set_table_for_first_display(
       EXPORTING
         i_structure_name     = 'SYST'
         is_hierarchy_header  = ls_hier_header
         it_toolbar_excluding = mt_function
       CHANGING
         it_outtab            = mt_tree )
Best Regards
Alex
if it help this is the dump
You attempted to access an unassigned field symbol
(data segment "-1").
This error may occur if
- You address a typed field symbol before it has been set with
   ASSIGN
- You address a field symbol that pointed to the line of an
   internal table that was deleted
- You address a field symbol that was previously reset using
   UNASSIGN or that pointed to a local field that no
   longer exists
- You address a global function interface, although the
   respective function module is not active - that is, is
   not in the list of active calls. The list of active calls
   can be taken from this short dump.

Answer 1

Hi!
The parameter, what you give for the i_structure_name and the it_outtab, must have the same structure.
If the it_outtab contains only 1 column, it cannot be the same with SYST structure.
Maybe if you declare it like this:
DATA: mt_tree LIKE STANDARD TABLE OF syst.
However this structure will never make you a tree-like ALV.
Check out the sample programs in SE38, called BCALV_TREE_*
Regards
Tamá