My guess is that your NumeroCourbe columns don't have any actual matches. Without seeing your data it's hard to say why they aren't matching. If the columns are numeric, try converting them to character. That will ensure that numeric precision issues aren't involved here. If they are character columns, try using Recode to Trim Whitespace and make sure the case matches between the tables.
Try turning on the options to include non-matches from both the main table and the with table. Then you can see that values that you think are matches aren't actually.
If you can post samples of the two tables we can better explain why there are no matches.