Boolean data type and flowfield

I need to be able to display and control a Boolean field in the Sales Line table, called s_checked, from the Pourchase Order Form.

I gave up on flowfield. I am trying with C/AL.

I added a new Text Control to my PO line sub form, and assigned a new
Boolean variable to it.

I am able to retrieve the Boolean value and display it in the new Text Control called p_checked.

The field is editable, so when the users change/check it in the PO form, I would like to be able to update the sales line field s_checked accordingly. I am using the following code under the OnValidate trigger of the p_checked control:


SalesLine.RESET;
SalesLine.SETRANGE("Line No.","Special Order Sales Line No.");
IF SalesLine.FIND('-') THEN BEGIN
SalesLine."s_checked" := Testing;
END

The field s_checked in sales line table doesn't get updated.
I then included the following line to the above code
CurrForm.UPDATE(TRUE);

But it caused error "CurrForm.UPDATE method can not be called from here.

How would I update this field?

Here is what I've done to tackle this:

__
Under OnAfterGetRecord event of PO Line form, I used the following code to retrieve the field from Sales Line Table:

SalesLine.RESET;
SalesLine.SETRANGE("Document Type","Document Type"::Order);
SalesLine.SETRANGE("Document No.","Special Order Sales No.");
SalesLine.SETRANGE("Line No.","Special Order Sales Line No.");
IF SalesLine.FIND('-') THEN
PriceApproved := SalesLine."Price Approved";


To write the updated value back to the Sales Line Table:
I used the following code under the OnPush event of the control:


SalesLine.RESET;
SalesLine.SETRANGE("Document Type","Document Type"::Order);
SalesLine.SETRANGE("Document No.","Special Order Sales No.");
SalesLine.SETRANGE("Line No.","Special Order Sales Line No.");

IF SalesLine.FIND('-') THEN BEGIN
SalesLine."Price Approved" := PriceApproved;
SalesLine.MODIFY;
END

__


Now sparky, feel free to suggest improvent, but spare me the russion wisdom.