I have multiple TCP/IP data points that are configured to pull every 15 min. In my watchlist I get the error "point is unreliable" on some of these points; however if I go to the data points not polling and do a manual pull do a manual pull I am able to get a value. Why would the point not be logging?

Here is my data point setup:

{
   "dataPoints":[
      {
         "purgePeriod":99,
         "setExtremeLowLimit":-179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368,
         "intervalLoggingType":"INSTANT",
         "dataSourceXid":"SWG_01_MB_1",
         "discardHighLimit":179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368,
         "deviceName":"MB-1",
         "enabled":true,
         "rollup":"NONE",
         "purgeOverride":true,
         "chartRenderer":{
            "numberOfPeriods":1,
            "type":"IMAGE",
            "timePeriodType":"DAYS"
         },
         "xid":"Current_c",
         "eventDetectors":[
         ],
         "textRenderer":{
            "useUnitAsSuffix":false,
            "format":"0.00",
            "type":"ANALOG",
            "suffix":""
         },
         "loggingType":"INTERVAL",
         "overrideIntervalLoggingSamples":false,
         "defaultCacheSize":1,
         "readPermission":"user",
         "setPermission":"superadmin",
         "intervalLoggingPeriodType":"MINUTES",
         "intervalLoggingSampleWindowSize":0,
         "tolerance":0,
         "purgeType":"YEARS",
         "plotType":"SPLINE",
         "intervalLoggingPeriod":15,
         "discardExtremeValues":false,
         "tags":{
         },
         "unit":"",
         "pointLocator":{
            "charset":"ASCII",
            "writeType":"NOT_SETTABLE",
            "offset":271,
            "slaveId":1,
            "slaveMonitor":false,
            "multiplier":1,
            "multistateNumeric":false,
            "registerCount":0,
            "range":"HOLDING_REGISTER",
            "modbusDataType":"FOUR_BYTE_FLOAT",
            "bit":0,
            "additive":0
         },
         "discardLowLimit":-179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368,
         "setExtremeHighLimit":179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368,
         "name":"Current_c",
         "chartColour":"",
         "preventSetExtremeValues":false,
         "simplifyType":"NONE"
      }
   ]
}

Is something wrong with my setup?