Cannot unlock the locked fields

Hi gurus,

I am changing the screen-input of the table control dynamically.

I can lock the columns.

The problem is, I cannot unlock them after I have locked them.

Is it possible to use only 1 button to do both the lock and the unlock functionalities?

During debugging, I found out that the screen-input always have the same values. In my first click to lock the button, screen-input has value of 1. So I changed it to 0 so that it will be locked. But when I click the button again, still, the screen-input has the value of 1. Thus, I can't unlock the locked button.

In the layout form, in the attributes - program tab, I have set the field to be input and output. Is this the cause why the screen-input always have the same value?

I've tried ticking the Without reset checkbox but still the same.

Thank you.

Benedict