Error "CALL_FUNTION_NOT_FOUND" in CRM2007

Hi All,

Customer is using crm2007 system. When he try to execute a prog "ztest" he is getting dump with CALL_FUNTION_NOT_FOUN & Exception is CX_SY_CALL_ILLEGAL_FUNC.

1. FM: POPUP_TO_DISPLAY_TEXT is existing in crm2007 system or not?

2. If yes, what might be other resons for this dump.

I searched for sap notes, still need more clarification.

Runtime Errors CALL_FUNCTION_NOT_FOUND
Except. CX_SY_DYN_CALL_ILLEGAL_FUNC

ShortText
Function module "POPUP_TO_DISPLAY_TEXT " not found.

What happened?
The function module "POPUP_TO_DISPLAY_TEXT " was called, but cannot be
found in the Function Library.

Error in ABAP application program.

The current ABAP program "ztest" had to be terminated because it has 
come across a statement that unfortunately cannot be executed.

Error analysis

  An exception occurred. This exception is dealt with in more detail below. The exception, which is assigned to the class 'CX_SY_DYN_CALL_ILLEGAL_FUNC', was neither
caught nor passed along using a RAISING clause, in the procedure
"FORM name" "(FORM)"
.
Since the caller of the procedure could not have expected this exception
to occur, the running program was terminated.
The reason for the exception is:
The program "ztest" contains a CALL FUNCTION statement. The name
of the function module to be called is "POPUP_TO_DISPLAY_TEXT ".

No function module exists with the name "POPUP_TO_DISPLAY_TEXT ".
All function modules are stored in the Function Library (SE37).

Possible reasons:
a) Wrong name specified. Particular attention should be paid
to upper/lower case and underscores ("_")
b) Transport error
c) If an enqueue/dequeue module has been used, the lock object
may not have been activated (ABAP Dictionary)

Please suggest me how to rectify this...

Regards,