ASA serial numbers not discovered on some ASAs. All other fields are discovered (ie SW version)

[mellwang]

We are discovering ASA devices but only two of the 20 collected have serial numbers.  The other are blank.   Every other filed is collected (i.e. SW version) only the serial number is missing.  

[Chris Camplejohn]

duplicate question.  See:

https://supportforums.cisco.com/discussion/13156056/asa-serial-numbers-not-discovered-some-asas-all-other-fields-are-discovered-ie