Doubts in F4 help

Hi,

I want to attach value help to a field. I also want to make that field as non-editable so that the user chooses only from F4 help. So i made an input field as non-editable and attached a F4 help to it. But when i try to choose value from the F4 help, it is not filling in the input field. Can some one help me with this.

Thanks and Regards,

Chander