I wish to lock the data entered once it is printed.

I have tried using a field call [Printlock]. when my print button is clicked, the code is:
me.printlock = Now()
(and then the print action code)

in form current, i have

if isnull (me.[printlock]) then
me.data.enabled = true
me.data.locked = false
else
me.data.enabled = false
me.data.locked = true

why doesn't my data lock when the print button is clicked? Do I have to refresh the data, or save the record, or requery, or what

Can anyone help?

Thanks a lot