Matrix total wrong

Hi as1195 
Please try the following 

Measure2 =
COALESCE (
    FORMAT (
        SUMX (
            SUMMARIZE ( Sales, Sales[Value], Sales[Column1], Sales[Column2] ),
            CALCULATE (
                VAR AllCells =
                    SUMMARIZE ( 'Sales', 'Sales'[Country], 'Sales'[Category] )
                RETURN
                    COALESCE (
                        CALCULATE (
                            DIVIDE (
                                SUMX ( AllCells, IF ( NOT ISBLANK ( [selection] ), [Selected Value] ) ),
                                [Total Value]
                            )
                        ),
                        1
                    )
            )
        ),
        "0%"
    ),
    0
)

Example=
IF ( SELECTEDVALUE ( Sales[text]) = "Number of cells", [Measure1], [Measure2] )