As stated I have a rebuilt transmission in my 2007 mini cooper s r52 and I have this code upon first start up after install. For history I bought this car at around 147k miles and drive it for around two weeks before the transmission started slipping. I got a code for 3rd gear solonoid and replaced them all. After replacement I got no more codes but after 5 minutes of driving 3rd and 4th would start slipping and sometimes cause my trans to lock into 3rd but no codes. I rebuilt the transmission new steels and frictions and now I got this code. I started it up once and tried to reverse out of my garage, she didn't move till 2.5k rpms. The car didn't jerk backwards but I did need high rpms to move it at all. I would like some help diagnosing and testing.

Thses are photos of my rebuild right before closing it up. https://photos.app.goo.gl/kV4rgZvNyFeGqvC18