Create Enhancement implementation in standard include

Hi,

I'm new to this enhancement procedures, but need to implement a small enhancement within a SAP standard include.

I have done the following:

- Pressed the enhance icon

- Choosed menu Edit->Enhancement Operations->Show implicit enhancement options

- Set the cursor on a line with an arrow in front

- choosed "create implementation" and choosed "code" in the next popup

- In the popup for selecting or creating enhancement implementations, I was choosing -> create enhancement implementation

- I have created an enhancement implementation, but got back to this selection popup. In there I can't find my new enhanc. implementation

- went to SE80 and actrivated my new enhancement implementation

-- > But in the popup to select an enhancement implementation, it can't still be found!

Can anybody explain me how to find it and how to proceed to add some enhancement code?

Thank you very much!