Why can't I make measures in PBI

[RonaldLieuw]

Hi,
I am trying to define two new measures for the table ToetsingNaf in PBI, but it does not let me do that.
The worksheet has two tables which I imported into PBI.
For the table ToetsingNaf I had to make two new columns Verschil 1 and Verschil 2 (formatted as %).

Verschil 1 = (ToetsingNaf[Tot_inv_Naf]- ToetsingNaf[GgM-Naf])/ToetsingNaf[Tot_inv_Naf]
Verschil 2 = (ToetsingNaf[GgM-Naf]-ToetsingNaf[Gg_Gdoc_Naf])/ToetsingNaf[GgM-Naf]

Instead of the new calculated columns I wanted to define two measures Verschil 1 and Verschil 2 instead of the columns.
Why can't I make these measures?

 

[RonaldLieuw]

I found the solution, this is the correct format:
Measure = sumx(ToetsingNaf, (ToetsingNaf[Tot_inv_Naf]-ToetsingNaf[GgM-Naf])/ToetsingNaf[Tot_inv_Naf])