I am trying to create a calculated control on a form as below

=amount * 2

all this gives is #name? error
the field exists and is either number or currency data type.
Even using the full table and field name syntax returns the same
I even created the code using the expression builder but the result is
always the same
Every website I have looked at, as well a couple of books say that this
should work.
Why can't I get the most simple calculated control to work. This is really
starting to make me hate msaccess.
Please help