FM HR_INFOTYPE_OPERATION inside class buider (SE24) is not working.

Dear Friends,

Here i need to update the infotype(105 - Communication details ) through webdynpro application , for this scenario im uning function module

HR_INFOTYPE_OPERATION to insert or modify the record but when i am calling this function module inside se24-methods it is throwing exception as given below

Runtime Errors ASSIGN_CASTING_ILLEGAL_CAST

Exception CX_SY_ASSIGN_CAST_ILLEGAL_CAST

i added initial size in internal table declaration then im getting exception like

An exception (CX_SY_NO_HANDLER) occurred

Message no. TPDA430.

Noe : tried ENQUEUE & DEQUEUE also INFTY SUBTY type everything is standared.

The same FM i have used in reports it is fine when i declaring the internal table with header line . but OO concept it is not possible to declare with header , so please help me to handle this scenario , or else is there any other classes are there to perform infotype operation ???