Creating a cumulative measure based on fixed values

Hi,

i'm having problems with creating a cumulative/running total measure. 

My situation is that i have two measure:

First one

Second one

The second measure is similar to the first one but on certain periods i had to force some values based on a field of the calendar table.

My goal was to create a cumulative measure based on the fixed measure (second one), so i created something like this:

here is what i get:

the first row of the cumulative measure is correct, but then it's like that the measure rather than getting the values from the fixed measure, goes to get the value from the first one

How can i resolve this? If something is not clear i'm willing to answer your questions.

Thanks in advance.