
It is important to note that you must not leave members blank on the inside dimension like this:

The correct row axis for what the above report likely means is this:

Note that the Accounts are now the outside dimension and the Products are now on the inside. This is called re-nesting the dimensions. This can be done by re-typing or moving the cells around, but it is usually much easier to use the Report Editor or the EPM pane and re-order the dimensions in the row axis section.
Although you are allowed to put blank rows anywhere throughout the axis, you must not put a blank column in between the nested dimensions like this:
