Wrong type in field number when printing Pro forma purchase order

Hi all,

I'm using AX 2012 Feature pack with CU3 

Kernel version: 6.0.1108.670

Application version: 6.0.1108.670

Solution version: 6.1.1108.670

Whenever I print Pro forma purchase order the system show error like this:

Error executing code: Wrong type in field number.

Stack trace

(C)\Classes\PSAPurchaseOrderController\runPrintMgmt - line 15

(C)\Classes\SrsPrintMgmtController\run - line 14

(C)\Classes\SysOperationController\startOperation - line 8

(C)\Classes\SrsReportRunController\startOperation - line 9

(C)\Classes\SrsPrintMgmtController\startOperation - line 14

(C)\Classes\SrsPrintMgmtFormLetterController\startOperation - line 14

..

(C)\Classes\FormLetterServiceController\afterOperationBody - line 6

(C)\Classes\FormLetterServiceController\afterOperation - line 7

(C)\Classes\SysOperationServiceController\run - line 70

(C)\Classes\FormLetterServiceController\run - line 3

(C)\Classes\PurchFormLetter\run - line 36

(C)\Classes\PurchFormLetter\main - line 67

(C)\Classes\FormFunctionButtonControl\Clicked

Have any one face this issue? Please help me.

Thanks in advance