SQL Server :: An Insufficient Number Of Arguments Were Supplied For The Procedure Of Function

I am maintaining a sql proc someone else wrote long ago. Basically I have a stored procedure which calls a function. If I try to run the stored procedure, or to make changes to it, and then run it, I am getting an error message which says "An insufficient number of arguments were supplied for the procedure of function dbo.GetRecentComment

This is very odd, because the stored procedure runs successfully when called via the C# code. Yet if it is run within query analyzer with the correct parameters, I get that error message. Here is a little peice of the stored proc which calls the function. And below that is the function which is being called. It appears that the second parameter passed to the function is optional, yet I am not sure. Anyway, here is some of the code from the proc, which calls the function.

SELECT CompletionDate, dbo.GetRecentComment(Request.RequestId) AS Comments -- This line is where the function is called FROM Request

Here is the function which is being called

ALTER FUNCTION [dbo].[GetRecentComment]
(
@RequestId int,
@SmallTag bit -- smalltag appears to be optional.
)
RETURNS VARCHAR(500)
AS
BEGIN