it doesnt seems to help. my code now look like this:

start:
sei
cld

;wait for vblank
lda $2002
bpl start

;activate background, set the name table ... etc
lda #%00000000
sta $2000
lda #%00011110
sta $2001

;set vram address to the first NT
lda #$20
sta $2006
lda #$00
sta $2006

;write data to NT1
lda #$01
sta $2007
lda #$02
sta $2007
....

lda #$00
sta $2006
sta $2006
sta $2005
sta $2005
loop:
jmp loop

and it doesnt show anything with fceultra. If i write to the second line of NT1 ($2020), i began to see some stuff at the top of the screen.

Any idea?