Topic: nfc-mfultralight : seems to read well, but not really

As said in the subject, i want to read a card (ultralight c)

>nfc-mfultralight r dump.mfd

NFC device: ACS / ACR122U PICC Interface opened
Found MIFARE Ultralight card with UID: 042299ea663480
Reading 16 pages |....|
Done, 4 of 16 pages readed.

I've got no dump file.
Why not file, and why only 4 pages read ?

thanks for your help