DotNetSQLDataReader.Read error

I have written code to copy the data from SQL to Nav 2017.

I am getting the error. Will you please help me
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WHILE DotNetSQLDataReader.Read DO BEGIN
DotNetSQLDataReader.GetSchemaTable;

TmpBufferTimeSheet."Staff Id":=DotNetSQLDataReader.GetString(0);
TmpBufferTimeSheet."Entry Date" :=DT2DATE(DotNetSQLDataReader.GetDateTime(2));
TmpBufferTimeSheet."Starting Time" :=DotNetSQLDataReader.GetDateTime(2);
TmpBufferTimeSheet."Ending Time" :=DotNetSQLDataReader.GetDateTime(3);
TmpBufferTimeSheet."Actual Work Hours" :=DotNetSQLDataReader.GetDecimal(4);

//TmpBufferTimeSheet.INSERT;
END;
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