Grand Sum Total is "error" and doesnt sum up

[mincii]

Dear Community

I have ridiciouls problem, which I couldnt found out, what exactly the Problem is: I have a calculation as shown below in the picture:

Here are the Measures:

Betrag = SUMX(Tankungen, Tankungen[Liter] * RELATED(Preis[Preis CHF/L]))

Betrag m Rabatt = IF([Kundengruppe] = "C", SUMX(Tankungen, Tankungen[Liter] * RELATED(Preis[Preis CHF/L])),IF([Kundengruppe] IN {"A","B","D"},SUMX(Tankungen, Tankungen[Liter] * (RELATED(Preis[Preis CHF/L])-0.03)), "Fehler"))

I know that "Fehler" comes from the "Fehler" of the measure.  When I am filtering everything looks great:

Does anybody know what I did wrong?

Thanks in advance. 

BR

[mlsx4]

Take into account that grand total doesn't meet this condition

[Kundengruppe] IN {"A","B","D"}

therefore, it will return "Fehler"

[mincii]

That means I can't fix this? Or what should I do instead?

[mlsx4]

What do you want to show in the grand total?

[mincii]

I want to show the sum grand total of all 4 (A,B,C,D) even If I have the exeption there with "C".

[mlsx4]

The only thing that cames to my mind is to generate another measure like this:

Betrag m Rabatt2= 
var A= CALCULATE( [Betrag m Rabatt], [Kundengruppe]="A")
var B= CALCULATE( [Betrag m Rabatt], [Kundengruppe]="B")
var C= CALCULATE( [Betrag m Rabatt], [Kundengruppe]="C")
var D= CALCULATE( [Betrag m Rabatt], [Kundengruppe]="D")

return IF([Kundengruppe]="",A+B+C+D, [Betrag m Rabatt])