Excel ignores given pattern-format of JasperReport

[schmatte]

Hello,

I've found a problem in JasperReports 3.7.1. I would like to subtract two date-fields with a formula in excel:

   <textField pattern="[h]:mm:ss">
         <reportElement x="730" y="10" width="134" height="20">
               <property name="net.sf.jasperreports.export.xls.formula" value="Q13-F13"/>
         </reportElement>
         <textElement/>
         <textFieldExpression class="java.util.Date"/>
   </textField>
 

The contents of the cells are the following:
Q13   24.03.2010  14:53:20
F13   24.03.2010  14:52:40

The shown result in Excel of the textField is: 0,000462963

This value of the cell is as same as the expected value of 40 seconds, but the output-format of the cell is wrong. The expected format with the given pattern is 0:00:40. I can get this output-style only, if I change the format of the result-cell in Excel manually. I tried it with and without the class-information of the textFieldExpression, but the result was still the same. Does anybody know, why Excel/JasperReports doesn't evaluate the given pattern "[h]:mm:ss"?

Thanks in advance.

Regards.