A single value for variaton '%{variation/}' for column '%{column/}' in table '%{table/}' cannot be determined. This can happen ...

A single value for variaton '%{variation/}' for column '%{column/}' in table '%{table/}' cannot be determined. This can happen when a measure formula refers to a column that contains many values without specifying an aggregation such as min, max, count, or sum to get a single result.