A: If you are using two calculated columns to make a diagram they must be created in the same calculation window at the same time rather than by two separate calculations. This is the way the program has been designed and the reason behind this is that as each of the variables is assigned a term, eg. A, B, C, etc which is used in the calculated expression. If there is more than calculation file then it would be possible to have duplicate terms being used in which reference different variables. Eg. A = SiO2% in the first calculation but A = Al2O3% in the second calculation. This information is all stored in the underlying XML and within the ioGAS file so by having all the calculations done together each variable is assigned a unique term.