An OLAP measure cell in Excel can end up with nothing in it. Behind the scenes, this is called null or #VALUE. Either can occur in a Teradata BI Repository MDX calculated cell or a cell that sums up a lot of MDX calculated values. One cause is a divide-by-zero error in an MDX calculated measure or calculated member. Check to ensure there are no zeroes in any denominator anywhere among the many calculations that might be aggregated into a displayed calculated cell. The null or #VALUE result depends on whether the database or Teradata OLAP Connector does the calculation.
Wrap the calculation in an MDX IFF statement for a consistent behavior (NULL); for example, IIF(Measures.Cost=0, NULL, Measures.Sales/Measures.Cost).