exception handling

[priyank dev]

hi experts,
               I want to display an exception,whenever a user doesnot makes
an entry in amount field.It has to display like 'Enter the amount'..so for
this i used swu_ewlis(tcode)  for exception and event fipp..but what should
be the LIS exception name?? i tried with pp01..but its displaying 'LIS
exception PP01 does not exist'
'
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