Pokerstove question

[juku]

Hi all,

my first post in 2+2 so I am not sure if this is the right forum.

I am currently trying to improve my move-in strategy in the endgame of NLHE tournaments.

Using Pokerstove to calculate the expectation of preflop distributions I found one result
I cannot explain:

Moving in with distribution
D1:= 55+,A7s+,KTs+,QTs+,JTs,T9s,A9o+,KQo,Qjo
has equity of 39.642% if called by distribution
D2:= 99+,AJs+,AJo+
Now I would like to know if the caller can improve by adding 88 to his calling range.
88 against D1 has 50.325% equity according to Pokerstove.
So I would assume that 88 should be added to the calling distribution D2.
But D1 called by 88+,AJs+,AJo+ has equity of 40.409%.
This (according to my calculation) would improve the overall expectation of the move-in!?

What I do not understand:

The calling distribution D2 consists of 84 hands (99+/36, AJs+/12, AJo+/36).
Adding 88 (6 hands) I would expect that

Equity of D1 vers. (D2,88) = (Equity of D1 vers. (D2) * 84) + Equity of D1 vers. (88) * 6)/90.
This yields: Equity of D1 vers. (D2,88) = (0,39642 * 84 + 0,49675 * 6)/90 = 0,40311
Which would decrease the expectation of moving in.

Do I miss something here? Is there a better place to post this?
By the way I am using Pokerstove version 1.21.

Thanks a lot for Your help!!