Having a problem with form_for

I was using formhelpers before with 3 fields that are dependent
dropdowns and using some ajax to perform the magic.
Now that's I've had to switch to form_for I'm finding one of two problems.
Renaming the fields to f.select generates an undefined method merge OR
leaving them be leaves them working in the form but the form is either
not grabbing the value or putting it into the database.

So this is the first field:
(btw - the name of the attribute the form should input too is "salary_id)
<%= select 'salary', 'id', Salary.find(:all).map {|s| [s.name, s.id]}%>
If I leave it like this, ajax works, but no db input.

if i add the f.select I get:
undefined method `merge' for [["Annual", 1], ["Hourly", 2]]:Array

I know this is a tough one , i now have a few hours trying to figure it out.
I'll take gueses even :slight_smile:

Stuart