The problem is caused by the Spanish locale, in which the decimal separator is “,” instead of “.” . One can circumvent the issue by forcing the Java virtual machine to use the US locale, instead of the OS default.
This can be done by editing the file (webMethods home)\MWS\bin\server.bat and, somewhere after the line saying
set SERVICE_NAME=…
Add the following new line:
set JAVA_OPTIONS=%JAVA_OPTIONS% -Duser.language=en -Duser.region=us