If the error says "OLEDB Error", more than likely the problem is in the data source. If you're using named query or view check if the query is working in SSMS.

Also, check data type of the error column in BIDS. Go to properties of the attribute, expand Key column, see data type is updated.

Is there a reason you're using Char for surrogate key? This could cause serious performance problems. Isn't INT data type solving your need?