What date, time and route?

We want to walk the kungsleden trail and start in Abisko on the 7th of august (my friends arrive in the morning). I now booked a train that arrives on the 6th. But the train from Hamburg-copenhagen and Copenhagen-stockholm is also fully booked. I would have to be in Stockholm on the 5th of august. 

@maike.lindhout Do you want to travel all the way from Hamburg to Stockholm on the 5th of August or are you planning a stopp in Copenhagen?

There are lots of trains from Copenhagen to Stockholm on the 5th of August with free seats. Check at sj.se

@seewulf @rvdborgt Any ideas how to get from Hamburg to Copenhagen on the 5th of August?

The rail planner is normally not up to date, as it only is updated once a month, so to be sure of the time table you better check the timetable and availability on the websites of the national railways. The bigger national railways, like DB (Germany) SBB (Switzerland) and ÖBB (Austria) cover several countries. 

The advice from the experienced travellers in the community is to use other ways to make reservations than the Interrail/Eurail website. You can look at the guide in the link:

https://community.eurail.com/train-connections-reservations-47/how-to-get-reservations-105

If you, after having looked at the guide, have questions about how to make specific reservation, please give your travel details (departure date, time and route) preferably in a new post, and you will get advice. 

I'm not sure why you would say that. I see plenty of availability, e.g. via the DSB website (30 DKK). You didn't say at which time, so: the first train leaves from Hamburg Altona, the others from Hamburg Hbf.

AND if full-there are only a fee direct trains HH-CPH and these are quite short too-use any hourly DB/RE till Flensburg and change to DSB-every 2 hrs-alltogether in maybe 30 mins longer as direct. Also from just over water/tunnelbridge from CPH are hourly SJ toget till STO-locals CPH-Malmo run ev15.20 mins

Thank you, I will take look at the sites from the railways. Its my first time interailing and I already discovered that the interrail website isn't the best..