I got an idea from you my problem is, that when I'm using move-corresponding, the <wa_dtab_modified> has no structure because it is created followingly
CREATE DATA dy_table TYPE table of (if_table_name).
ASSIGN dy_table->* TO <it_dtab_modified>.
create data dy_line1 like line of <it_dtab_modified>.
ASSIGN dy_line1 to <wa_dtab_modified>.
so all I have to do is to create <wa_dtab_modified> differently and I think the best way is the RTTS where I define the structure or with the CALL METHOD cl_alv_table_create=>create_dynamic_table where I define the fieldcatalog which define the structure. So it should work, but I have to try it out
Then I'll inform you about the results.