Error with join

Hello,

I'm trying to make a junction with a connection in ArcGIS 10.1 OLE DB Provider for SQL Server 2008.
When performing the join between the table with my sql table shapefile values ​​are null.

I checked that the fields are indeed equal, even copied the records from SQL table to shp and yet when I run the join information is as follows:

The number of matching records for the join:
- No matches found by joining [REGISTRATION] from <Q20> with [REGISTRATION] from <dbo.vwIMOVEL>.

A curious fact is that if I export my table to dbf can run normally join!
But in my case I need to work with the remote connection on sql.
Do you know any way to help me?

Sincerely,

Joab