I don't know how QueryAnalyzer calls your functions, but I know this error.
Usually, when you have user-defined functions, you need to prefix the function with the schema name.
So if your function is in schema "dbo", and the name is "fnPadLeft", you need to call the function in code like this:
SELECT
id
,some_field
,dbo.fnPadLeft(some_other_field)
FROM YOUR_TABLE_NAME
If you call it like this:
SELECT
id
,some_field
,fnPadLeft(some_other_field) -- lacks dbo.
FROM YOUR_TABLE_NAME
Then you'll get "no such function".
This only happens to scalar functions btw. (you specifically mentioned this), table-valued functions (and all other non-function things) are not affected by this "feature".
It might also be that you have the same functionname in two schemas (also take a look at the functions in the master database). Maybe your "other functions" are table valued functions.