Error in the manual?

[llantones]

Hello:
I think this text from manual is incorrect:

http://www.timetabling.de/manual/FET-manual.en.html#id_19

A set of activities should be instructed on different days, but they must not instructed on different days.


The correct:
but they must not be instructed on different days.

and the two sentences means the same, then I don't understand.

Thanks.

[Volker Dirr]

but they must not be instructed on different days.

Oh, sorry. may english is not very good. i think you are right. i will fix that. thank you for reporting.

and the two sentences means the same, then I don't understand.

to say it with fet terms:
must mean "100% weight"
should mean "a bit under 100% weight"

i am not an english nativ speaker. so please correct me if that is wrong.

[llantones]

Ok, I understand now.
Thanks.