SSAS Calculated measure with SCOPE. I'm building an SSAS OLAP cube on Meteorological data. Some of this data can be totaled (eg rainfall) and some can't (like wind direction).

I want totals, but only on data sources where it makes sense. (Where the interpolation method = 3.)

I've tried adding SCOPE with this: 

SCOPE ([Measures].[Total]); 
SUM([Data Source].[Interpolation Method].&amp;[3],[Measures].[Total]); 
END SCOPE; 


And get warnings: 


  Invalid query syntax. A valid MDX or DAX query was expected


and: 


  One or more errors were encountered in the MDX script


What am i missing?
I don't have your SSAS database so I can't test the syntax, but I believe you would need to write your MDX as follows (notice the THIS= addition):

SCOPE ([Measures].[Total]); 
THIS = SUM([Data Source].[Interpolation Method].&amp;[3],[Measures].[Total]); 
END SCOPE; 


See the documentation for syntax details.