iReport Excel Report Fails with Error

[marciokoko]

I created a simple xls file with 4 rows:

1 - year

2 - clientname

3 - invoice

4 - value

I create a crosstab placing the year in rows, the clientname in columns and value in data.  When I try to preview it I get this error:

Error filling print... Error incrementing crosstab dataset
Warning:  Property storage name for 5 is empty - setting to Root Entry...and some jaspereports.engine.fill lines