summerize differently depending on filter

Anonymous 

Which table / column represents the costomer?

The customers are coming from a table, that selects column from table

relationships are:

Anonymous 

Please try

Lost_amount3 =
SUMX (
CROSSJOIN ( VALUES ( 'Date'[Monta] ), VALUES ( 'Lost_prep'[Cliento] ) ),
[Lost_amount]
)

Hmmm, now it summarizes, but it has the wrong amount. Lost_amount should be the same as Lost_amount3

Anonymous 
Please try

Lost_amount3 =
SUMX (
    GENERATE (
        SUMMARIZE ( 'Date', 'Date'[Jahr], 'Date'[Monta] ),
        CALCULATETABLE ( VALUES ( 'Lost_prep'[Cliento] ) )
    ),
    [Lost_amount]
)

It summarized too much. So, I thought it would be better with a filter

but even this does not change something. The total still not a summary

Is this a relationship issue?

Anonymous 

Not sure to be honest. Please try

Lost_amount3 =
SUMX (
GENERATE (
SUMMARIZE ( 'Date', 'Date'[Jahr], 'Date'[Monta] ),
CALCULATETABLE ( VALUES ( 'Lost_prep'[Cliento] ) )
),
CALCULATE (
[Lost_amount],
CROSSFILTER ( 'Date'[Date], '2_Abfrage_Orderline'[Date], BOTH )
)
)

Lost_amount3 does not match with Lost_amount. DAX seems to be very complicated

Anonymous 
It is better to connect and have a direct look at the data. Let me know if this is possible perhaps tomorrow noon Dubai time.

Oh this would be so great. How can we connect?