Replace function not working

Hi,
I posted a request here and am still working on it when I landed on this bug.

select top 10 replace(comma_separated_string,',','giveaverylongp assagehere') from table

The function works fine if the comma separated string is small or if the passage is small. It fails for long passages..

Is this a mssql bug?What's long? Replace works fine for me on 8000. Does it break off at 1024 in the Analyzer, while it's len(..) says otherwise?sql