convert datetime gives me errors

[crystalhelp]

The following statement works in some spots and not in others: convert(datetime,b.dateval) >= DateADD(year,-@Years,GetDate()) and convert(datetime,b.dateval) <= getdate()

b.dateval is a char and @years is an int.

It works when I have it in a basic where clause, but it doesn't work if I have it in a where clause that is 3 where clauses deep. That is the only difference I can figure out. The error I'm getting is Server: msg 242 - The conversion of a char data type to a datetime data type resulted in an out-of-range datetime value.

Do you know why?

 

[SQLSister]

You have data in there which is not real date data and it cannot convert it.

Questions about posting. See faq183-874

 

[crystalhelp]

I've thought of that. Except, when I replace

convert(datetime,b.dateval) >= DateADD(year,-@Years,GetDate()) and convert(datetime,b.dateval) <= getdate()

with

DATEDIFF(day, convert(datetime,b.dateval), getdate()) <= @Years*365)

which also has the convert date statement, it doesn't give me the error, which made me think the error message was wrong.