Has it actually failed for you or was it just the note you spotted?
Are they connecting to a SQL Server?

I found the following MS Article
[http://blogs.office.com/b/microsoft-access/archive/2012/03/19/access-2010-how-to-write-expressions-for-web-queries-forms-and-reports.aspx]

It might Server related.
Scroll 1/3 of the way down.

Strict Type Coercion

One of the most difficult changes for traditional Access users to get used to is likely to be the addition of strict type coercion on the server. Access client will allow you to compare values stored in mismatching data types. For example, users can create a query that compares the value of a date/time column to the string ?2009-10-02? and they will receive results from the query appropriate to the comparison. However, the same query will fail on the server because the user is attempting to compare a string and a date value. The only exception to strict type coercion is between dates and numbers, mainly because they are both stored internally as numeric values. For all other data types, implicit coercion is blocked on the server.

Because of this restriction, there are two common design considerations you should keep in mind when working with different data types.

When you work with Boolean values, always use the constants True and False instead of the numeric values 0, -1 or 1.
When you compare strings to numeric or date/time values use FormatNumber(), FormatPercent(), FormatCurrency() or FormatDateTime() functions to convert the field value to a string in order for the comparison to work on the server.

Alex