How to set a validation Error

[meindert]

Hi

I'm using the GwtRpcDataSource and am strugling to get a validation message back to the user when doing a update

Map<String, String> errors = new LinkedHashMap<String, String>();
errors.put(ex.getValidationExceptionFieldName(), caught.getMessage());
response.setErrors(errors);
SC.logWarn(ex.getValidationExceptionFieldName() + ":" + caught.getMessage());
processResponse(requestId, response);

I get the message that:
Server returned VALIDATION_ERROR with no error message
What am I doing wrong? (how do I give the error message)

Here is the console output:

10:37:41.876:MUP3:WARN:Log:brandId:Opel(OP) is already linked to oem GM
10:37:42.030:MUP3:WARN:RPCManager:Server returned VALIDATION_ERROR with no error message., response: {clientContext: Obj,
status: -4,
errors: Obj,
context: undef,
startRow: 0,
endRow: 0,
totalRows: 0}