Hi,
The error is because the connector expects the event opcode and flag in the data.
Either you add "i,n," before each line in the data where "i" stands for insert opcode and "n" stands for normal event flag. Or you can set two properties in the connector All Properties section. The properties are "addcsvopcode" and "addcsvflags". I have added the sample xml snippet for those properties in the connector.
<property name="addcsvopcode"><![CDATA[true]]></property>
<property name="addcsvflags"><![CDATA[normal]]></property>
Also, I will suggest adding some data too to each event apart from the key when testing.
Hope this helps.