That seems correct.
Did you enter an alias for that column field in the cross-tab? It'd be in the Cross-tab Expert on the "Customize Style" tab. Select that column and see if there is anything in the "Alias for Formulas" box. It looks like the name you use in GridRowColumnValue has to match that alias. The default should be the original field name, but if you change the alias, it appears that you have to use that alias.
James