Hi all, newbie just docked in port

Hi all.
I have only recently joined SUBSIM and am looking forward to some great help,advise,suggestions and may be downloads.

I have been on SH5 for a while now & have managed to get myself to Artic Convoys and now find myself stuck.

I have sank the cruisers(Close Cover) and the tonnage bar has filled up.
I have been patrolling,using various search patterns,between Iceland & Arkhangelsk,calling into Murmansk and waiting for a while there.

For some reason whenever I find a convoy(which is rare) I can sink usually 5 or 6 ships but the tonnage bar will not fill up.

I have also downloaded Wolves of Steel,but this seems not to run and it tells me that there is a corrupted CRC file.

Any suggestions,help and/or advice would really be appreciated.

P>S, sorry this is such a long post