Cant add fields to any list..

[kouwearie]

Uhhm im havin an awkward issue..
Suddenly i get an error when i want to add an element to any list.

errormessage:
You cant add fields to this list

I havent done anything weird, iv been adding this whole noon without any issues...
What can cause this?

 

[troester]

In Fabrik Options/List check if you've set "Alter field types"=NO