"FPGrowth: parameter must_contain duplicates items."

Hi,

I use RapidMiner 4.6.0, and I want to do FPGrowth with parameter "must_contain."

So I set must_contain to "geneexpression = dn" (gene expression can be either up or down).

A resulting item set contains both "geneexpression = up" and "geneexpression = dn" (at the rightmost).

Then the process dies at AssociationRuleGenerator. See the message below.

G Mar 19, 2010 9:38:20 PM: [Fatal] NullPointerException occured in 1st application of AssociationRuleGenerator (AssociationRuleGenerator)
G Mar 19, 2010 9:38:20 PM: [Fatal] Process failed: operator cannot be executed. Check the log messages...
         Root[1] (Process)
         +- Input[1] (ExampleSource)
         +- Nominal2Binominal[1] (Nominal2Binominal)
         +- FPGrowth[1] (FPGrowth)
here ==> +- AssociationRuleGenerator[1] (AssociationRuleGenerator)


Thank you for you help,

Chatchawit