Aircraft on PPI scope
 

I've played SHIV for quite a while with various mods and whenever I get an alert of a radar contact but nothing on the PPI I know it's an aircraft and the SJ couldn't detect aircraft except at very low level and the alert is from the SD which was range only on an A scope.
However, I been trying some new mod combinations and discovered I could see aircraft on the PPI, great! I then tried some more mods and now I can't see the aircraft on the PPI anymore. I always start mid 1943 in a Balao class and my current mods are: TMO overhaul 2.5, RSRDC TMO V502 with patch, OTC for TMO, OTC realistic scopes, TMO US Radar from start TMO, TMO alternative JS radar performance, TMO fix for TDW DC water disturbance and Traveller mod, in that order.
In 1943 don't have SV radar and I know I was seeing aircraft on the PPI in 1943. Any ideas?
Also, is there any way you can have a Tench class earlier in the war?

I figured it out its the TMO fix for TDW DC mod that was the problem. When I took that out I started to see aircraft on the PPI again.