I have some frustration on TMA
"Redbook" says the dual sensor tracking should represent the truth, but looks like it doesn't work in DW

I am tracking an oiler ship, I got it on sphere passive and TA. I try to find the place where the two line connect but it doesn't work. After 20 min 's frustration on where to put the ruler, I turned the truth on. Mark the accurate location, and this is a TMA solution to reflect the ship's accurate location.
I don't understand why there is a huge difference from the two dots on the top. Did I do something wrong?
Thank you