Once in a lifetime and I was robbed!

[Telemon]

Greetings,
I've been playing SH since it first appeared as SH1 right through to SH3 with looks at SH2, 4 and 5. (i.e. Years and years). Then my dream comes true.

Last night, Friday I'm on patrol in my current career, Sep 19 '40 (at 90% realism for the first time) patrolling in the 'gut' of Gibraltar when my sonar man reports warships approaching fast from the West.
First looksee - nothing; wait look again- Wow! Task force consisting of two Nelson class BBs three CLs and a slew of DDs. Range c9000+
Start the plot -'Lord' they are coming fast; 20+kts. Frantically plotting. Estimate 23kts and one BB will pass about 1200 mtrs. ahead of me. Set torps for 13mtrs; range 1200. Barely time to think. Fire all four bow tubes and " Down 'scope and dive to 130 mtrs. Silence. Wait. Then Bang, bang, bang, bang four hits!
A sub skippers dream come true. Sonar reports nasty noises (sad music playing).

I cheat! Key F12. I've just got to see this. Yes she's down by the head and I watch her go down. Yippee!!!
I wait for a long while as the DDs make a few runs but they don't drop any DCs (which I find strange).
Eventually I come to the surface and send a status report. No mention of the BB being sunk at all. I check my log (H key) and nothing there either. I can't believe it.

Can some one explain please?