created an attachment (id=169641)
test report

description:
  npe is thrown out when y value set to string type in bubble chart

test build:
birt2.6.0 v20100524-1222

step to reproduce:

1. use the report attached
2. preview it

expect result:
report can preview 

actual result:
nep is thrown out

error message:
caused by: java.lang.nullpointerexception
	at org.eclipse.birt.chart.extension.datafeed.bubbledatasetprocessorimpl.populate(bubbledatasetprocessorimpl.java:287)
	at org.eclipse.birt.chart.internal.datafeed.dataprocessor.fillseriesdataset(dataprocessor.java:1350)
	at org.eclipse.birt.chart.internal.datafeed.dataprocessor.generateruntimeseries(dataprocessor.java:813)
	at org.eclipse.birt.chart.internal.datafeed.dataprocessor.generateruntimeseries(dataprocessor.java:1450)
	at org.eclipse.birt.chart.internal.datafeed.dataprocessor.generateruntimeseries(dataprocessor.java:507)
	at org.eclipse.birt.chart.factory.generator.binddata(generator.java:652)
	at org.eclipse.birt.chart.reportitem.chartreportitempresentationbase.binddata(chartreportitempresentationbase.java:683)
	at org.eclipse.birt.chart.reportitem.chartreportitempresentationbase.onrowsets(chartreportitempresentationbase.java:797)
	... 41 more
fixed a npe issue in ubbledatasetprocessorimpl.
verified in daily build v20100525-0630