custom field for expense dates

I am trying to create a script that will copy the expense date into the line of each expense entry, since the default field is currently not available for reports/saved searches.  Here's the script I have so far, but it's not working.

function enterDate

{
var date=nlapiGetCurrentLineItemValue(type,'expensedate');

nlapiSetCurrentLineItemValue(type,'custcol1',date,true,true);
}

Any ideas what I'm doing wrong?

Also, I did just a simple thing by creating the custom field (custcol1) and having the default value/formula = {expensedate} and not storing value.  this worked as it showed the values on screen, but when I go to use this field in a saved search, it says Error: Field Not Found!  Argh!!   This tells me the field is accessible to some degree, just not for any purpose of value!