AX 2009 : how to solve the problem of the sequence number

why the error message always appears when i will make a new sequence number

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Error message : "Cannot create a record in Number sequence (NumberSequenceTable). Number sequence code: 1702, 1702.

The record already exists. "
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My program with X++ :

       select forupdate NumberSequenceTable;

        NumberSequenceTable.initValue();

        NumberSequenceTable.NumberSequence= 1702;

        NumberSequenceTable.Txt= 1702;

        NumberSequenceTable.Lowest= 1;

        NumberSequenceTable.Highest= 9999;

        NumberSequenceTable.NextRec= 1;

        NumberSequenceTable.Format= 1702+"####";

        NumberSequenceTable.Continuous = NoYes::No;

        NumberSequenceTable.CleanAtAccess= NoYes::No;

        NumberSequenceTable.InUse= NoYes::No;

        NumberSequenceTable.CleanInterval= 0;

        NumberSequenceTable.CG_NumSeqModule= NumberSequenceModule::Inventory;

        NumberSequenceTable.insert();

 thank you and sorry to my english.