[Typo3-dev] Cannot get rid of "update needed,changing field"in EXT

[Arco]

In my extention I added two fields in the ext_tables.sql
In the EM -> my_extention the database needs an update.
After the first update (which is expected) I still have an error:

  Database status:	Table error!
  Probably one or more required fields/tables are missing in the database!

  Update needed:
  Changing fields

	ALTER TABLE tt_content CHANGE tx_gooffotoboek_path tx_gooffotoboek_path           
        mediumtext DEFAULT '' ;
	Current value: mediumtext
	
        ALTER TABLE tt_content CHANGE tx_gooffotoboek_webpath 
        tx_gooffotoboek_webpath mediumtext DEFAULT '';
	Current value: mediumtext

When looking in the database the value is correct.
What did I oversee?

Arco