How to edit HLAs in EE Keeper ?

Hi,

I picked a wrong HLA for Minsc (2 x power attack instead of critical strike) so I wanted to edit it in EE Keeper. I removed it with "Mem -" in Innate abilities and it worked, but when I want to memorize the new HLA I get this message "Minsc has reached the maximum number of spells memorizable for this level". What am I doing wrong ?

Thanks