To raise an XPath issue on a file, the XPath expression has to return a boolean. As your last expression is the result of the concat function, it returns a string.
I suggest using: count(//jsp-descriptor/jsp-param/param-name[text()='page-check-seconds']) = 0
One more thing: if the pattern of the XPath rule is weblogic.xml, it will only look for a file named weblogic.xml at the root of the project. You may want to set the pattern to **/weblogic.xml to scan all files named weblogic.xml.