Error in Runbasebatch class

Following error faced when execute batch :-

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Microsoft Dynamics AX Debugger
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Error executing code: Wrong argument types in variable assignment.

Stack trace

(C)\Classes\SYNInventSumBatch\unpack - line 12
(C)\Classes\xSysLastValue\getLast - line 29
(C)\Classes\RunBase\getLast - line 16
(C)\Classes\RunBaseBatch\getLast - line 12
(C)\Classes\RunBase\promptPrim - line 8
(C)\Classes\RunBase\prompt - line 12
(C)\Classes\RunBaseBatch\prompt - line 30
(C)\Classes\SYNInventSumBatch\main - line 5
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OK
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