"...billing calorific value is missing" billing error message

Hi,

I need to bill a gas contract but when I run EASIBI I get the following error message: ...billing calorific value is missing. This happens because the calorific value/calorific value procedure table is not maintained for the year 2013 and I cannot maintain it (when trying to change it via EA71 I cannot check the "maintained" checkbox). How can I do that?

Please help me with this.

Thank you,

Best regards,

Balazs