title: Error while using POI API
body: <p>I am using selenium webdriver. I am writing to excel file using POI API.
   I am getting following error:</p>
  
  <pre><code>org.apache.xmlbeans.impl.values.XmlValueDisconnectedException
  at org.apache.xmlbeans.impl.values.XmlObjectBase.check_orphaned(XmlObjectBase.java:1258)
  at org.openxmlformats.schemas.spreadsheetml.x2006.main.impl.CTXfImpl.getXfId(Unknown Source)
  at org.apache.poi.xssf.model.StylesTable.getStyleAt(StylesTable.java:183)
  at org.apache.poi.xssf.usermodel.XSSFCell.getCellStyle(XSSFCell.java:427)
  at org.apache.poi.xssf.usermodel.XSSFCell.getCellStyle(XSSFCell.java:63)
  at org.apache.poi.ss.usermodel.DateUtil.isCellDateFormatted(DateUtil.java:280)
  at com.bcatman.util.Xls_Reader.getCellData(Xls_Reader.java:149)
  at com.bcatman.base.TestBase.readExcelData(TestBase.java:159)
  at com.bcatman.suite.CatalogImportExport.ImportSimpleExcel.testcaseImportSimpleExcel(ImportSimpleExcel.java:89)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
  at java.lang.reflect.Method.invoke(Unknown Source)
  at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:84)
  at org.testng.internal.Invoker.invokeMethod(Invoker.java:714)
  at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:901)
  at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1231)
  at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:127)
  at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:111)
  at org.testng.TestRunner.privateRun(TestRunner.java:767)
  at org.testng.TestRunner.run(TestRunner.java:617)
  at org.testng.SuiteRunner.runTest(SuiteRunner.java:334)
  at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:329)
  at org.testng.SuiteRunner.privateRun(SuiteRunner.java:291)
  at org.testng.SuiteRunner.run(SuiteRunner.java:240)
  at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
  at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86)
  at org.testng.TestNG.runSuitesSequentially(TestNG.java:1224)
  at org.testng.TestNG.runSuitesLocally(TestNG.java:1149)
  at org.testng.TestNG.run(TestNG.java:1057)
  at org.testng.remote.RemoteTestNG.run(RemoteTestNG.java:111)
  at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:204)
  at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:175)
  </code></pre>