Hello Ravi, I had experimented with both of the above before posting this question and I mention one of them in my original post: "So I removed the column I used as a measure and introduced a measure column from the base table which is defined as a numeric column and bingo the view works with concatenated columns as expected. I then re-introduced the previous column as a second measure and the validation step fails again with the same error." I therefore concluded: "From this it appears that you must have only numeric measure columns from the base table for you to create any concatenated string column (as a Calculated Column). Since this is fairly straight forward to implement in a raw sql, I think this is perhaps an issue with the studio unless I have missed a step somewhere."
Now I am getting the same validation errors in other places where I am using row counts. For example, I couldn't graphically design a calculation view based on two existing views both of which have row count (as measure) and work fine on their own. When I combine these views as a union, validation complains about the columns where row counts have been used (the measures) and yet it compiles these views individually without any errors and produces the desired results! My workaround then was to hand crank the calculation view but I think the graphic designer should cope with such a scenario. It looks like the treatment of row count is inconsistent across different views.
Kind regards,
Ramesh