Your error is coming from the line that parses the enum. Use Enum.TryParse instead:
AutotransferMessageType msgEnum;
var enumPrasedOk = Enum.TryParse(_searchCriteria.MessageType, true, out msgEnum);
if(enumPrasedOk){
//Do something
}else{
//Handle case where enum was not found for some reason (if need be)
}
Also please note that you can not look up the enum this way using it's description (in your case they are the same so it is ok).