Sick Leave balance is 15 Days but he is getting Error

Summary:

A person is trying to apply sick leave but getting below error, there is no validation formula , accrual plan is using and Accrual matrix formula is also being used and nothing, however this person applied two times this year sick leave one is for 10 days and 5 days respectively but both times it was rejected by manager and currently these are in denied mode , if system has allocated these leave then how can I retrieve them , if any process need to be run please advise, or any other solution then please share

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