It won't confirm because the grandparent and parent of your child transaction aren't confirmed. The grandparent transaction was also paid with a really low fee(51.573 sat/B).
I did the math for you.
Grandparent + parent + child = total transaction size:
3878 Bytes + 226 Bytes + 225 Bytes = 4329 Bytes
Add up all paid fees:
200000 Sat + 200000 Sat + 200000 Sat = 600000 sat
Divide total paid fees with total transaction size:
600000 / 4329 = 138.6 Sat/B
Subtract to find difference needed:
450 Sat/B - 138.6 Sat/B = 311.4 missing Sat/B
To sum it up.
On average, the three transactions were paid with a fee of 138.6 Sat/B each.
The fee needed to confirm within 6 blocks is presumably around 450 Sat/B right now.
So the three transactions are short 311.4 Sat/B to reach the target of 450 Sat/B.
Probably Rob can use reaplace-by-fee in this case to make it faster. – CoperNick – 2017-12-30T16:26:49.763
How can I do that? I used blockchain.info api to make the transaction – Rob – 2017-12-30T16:49:54.403
where can I see the parent / gradnparent - transactions on blockchain.info? – ndsvw – 2017-12-30T17:19:25.367
@Rob You can't on most exchanges, however your fee of 138.6 Sat/B will confirm within 48-144 blocks...seems like it just got confirmed now. – Chak – 2017-12-30T20:44:49.890
@Alpha just follow the trails where the unconfirmed outputs originate from. – Chak – 2017-12-30T20:45:14.800