Problem migration SQL Server to MySQL with SSIS (no replies)

I'm trying to migrate data from SQL Server to MySQL using SSIS control. The problem is that not all rows are copied because there is an exception:

An exception has occurred DURING data insertion, the message Return from the provider is: Unable to cast object of type 'System.Int16' to type 'System.Char []'.

Only happens in the tables that have fields of type NULL. When you insert a NULL appears this exception.

Thanks for your help.