Token Bars cannot be linked to hp

Hi everyone, i am running a bought adventure "Evil of the Water" and want to have the provided tokens (here the owlbear) to represent the hp. It seems so easy - i access the token settings. There are the Token Bars to be modified - it says "You can choose to have the bar represent an attribute" - the bars ares filled with numbers - the red one has the hp but the Attribute box says "none". Trying to change that box to "hp" does not have an effect there, just opens the "controlled by" box. How can i get the attribute box to have the hp in there. Are there scripts in the background that prevent me from choosing? Please help Thanks Brigitte aka Scerijne

Found the mistake - there was no character sheet connected to the token my bad

FYI, it's not a good idea to link the HP attribute of a character sheet if the sheet will be controlling multiple tokens: for instance, one Goblin character sheet that is used for a group of 5 Goblin tokens. If the HP bar is linked, then when one token takes damage, ALL the tokens will take damage. It's better in these types of cases to just have the current and maximum HP for that NPC predefined in the individual tokens. That way, when one token takes damage, the others won't also change.

Thanks a lot, that is useful to know!