created an attachment (id=171368)
screenshot

description:
"the extendeditem must be able to access one data set." is shown when a chart inherit columns and groups from container.

build number:
2.6.0.v20100607-0630

steps to reproduce:
1. preview the attached report design.

expected result:
no error.

actual result:
see the screenshot.

error log:
n/a
created an attachment (id=171369)
report design
fixed by ignoring the validation for chart templates
no error in problems view any more.

verified in build (2.6.1.v20100617-0604), closed.