NiFi Expression Language (NEL)  does not read content of the FlowFile. The RouteOnAttribute processor never looks at the content of a FlowFile. So verify your source FlowFile has attributes set with valid numeric only values.
So your inbound FlowFile would need to have two attributes on it already:
Note: NiFi is case sensitive as well.
And both these attributes need to have assigned values to them.
The NEL statement you have will return the value assigned to the FlowFile attribute "cont" and check to see if it is less than the value assigned to the FlowFile attribute "CONTADOR". If that resolves to "True", the FlowFile will be routed to the connection containing the new dynamically created "CONTINUE" relationship. Otherwise, it will route to the "unmatched" relationship which you appear to have auto-terminated.
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