Hi Deepa,
Then possible issue is WONUM generated through add method but while save some exception occur because of that work order data not saved. Please check system log and error log for this issue.
In past we encounter this issue where user was getting success message of work order generation, but work order not generated in WOTRACK table on further analysis we found below exception in system logs
In past we encounter this issue because of below exception.
psdi.util.MXApplicationException:system#unsetDiscardable
at psdi.mbo.MboSet.setDiscardableFlag(MboSet.java:6248)
at psdi.mbo.MboSet.setFlag(MboSet.java:6191)
….
My suggestion is please check logs you will surely get some hint for this issue.