Your old database has the function. Your new one does not. You likely won't find any web reference to it because it's proprietary (it's a user defined function, or UDF).
Open your old db where this works and ctl+G to open your vb editor and ctl+F and search for the name. Make sure you select to search the whole project. You'll either need to copy the function or import the whole module, depending on what you need. Take note of what kind of module it is in - form, report, class or standard and post back if you need help after you find it.
EDIT
I guess I could also point out that you may have copied over the function but its name is now misspelled, or you have it in your new db but its scope is such that it isn't visible to your query.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.