Hello All,
Thanks a lot for your help.
The problem of showing blank lines got resolved. 
I just passed:
l_wa_layout-detailinit = abap_true
and used this layout structure in the Method:
CALL METHOD o_alv->set_table_for_first_display
EXPORTING
is_variant = l_wa_disvariant
i_save = l_c_a
is_layout = l_wa_layout
After, this all the rows with intial values got displayed.