In OLAP binding mode, the FieldName property must specify the full name of the bound measure or dimension.
For dimensions, the full name is composed of a dimension's name, followed by a hierachy's name, followed by the name of a level(s). All names should be wrapped within square brackets and separated from one another using the dot symbol. Example: "[Customer].[Customer Geography].[Country]".
For measures, the full name is composed of the "[Measures]." string followed by the measure's name. Example: "[Measures].[Sales Amount]".