InvocationTargetException with XLSX generation

Hello. I’m using reports and getting an exception, for which i cannot find a source of a problem. any ideas about where to search for it?

An error occurred while rendering band [mySampleBand]. Template name 
[myTemplate.xlsx] Report name [mySecondReport]

I’m sure to use working template cos it works fine for my first report. The groovy code for this band is:

result = []
List saved = []
transactional { em ->
    def query = em.createQuery('select c from sample$Entity c')
    saved = query.resultList
saved.each { item ->
    result.add(['item' : (item) ? item : ''])
return result

If a have correctly understood a list of entity instances (their namepatterns) should be printed in ‘‘mySampleBand’’. Right?
Which attributes are included to instance name?
Could you share the whole exception with stacktrace?

Try to debug the error. Find the “protected void writeBand(BandData childBand)” method in com.haulmont.yarg.formatters.impl.XlsxFormatter.