Wikimedia Bugzilla is closed!

I've got the following code:

{{#subobject:testNumbers
|Page={{PAGENAME}}
|Amount=10000
}}
{{#subobject:testNumbers
|Page={{PAGENAME}}
|Amount=20000
}}
{{#subobject:testNumbers
|Page={{PAGENAME}}
|Amount=30000
}}
[[Amount::{{#ask: [[Page::{{PAGENAME}}]]
|?Amount
|format=sum
}}]]

The result of the sum on the screen is 60000. The property 'Amount' of the page shows 60.
Language is Dutch.

My strong guess is that the #ask is returning the value "60.000", because your wiki is in Dutch, and the "[[Amount::" call is getting confused by that, thinking that it means 60. The issue with "," vs. "." as number separators has caused problems in SMW before.

You're right, indeed it returned 60.000. 
And indeed if I do [[Amount::60.000]] it is stored as 60 as well.
I'll submit it as an SMW bug.