Millisecond Forums

After the end of each block, I want the participants to receive a feedback related to the number of blocks that have been completed. According to this https://www.millisecond.com/support/docs/v6/html/language/properties/currentblocknumber.htm
I created a Break page
<page Break>
You have now completed block <%expt.currentblocknumber%> out of 6.
^^Please feel free to take a short break now. Before you continue, we remind you that the words on the sides of the screen may have changed.
</page>
But it sais that “Expression 'block.currentblocknumber' is invalid. Expression contains an unknown element or property name.”
Why is this happening?

I also try to find a way to show a “thank you” page (instead of break) if the blocknumber is number 6 (the last one), but I m not familiar with expression syntax. Could you help me?
Thank you in advance