Generally for recovery scenarios I dont use functions. I 
rather use the keyword or mouse operation which is much 
simple.
However based on the question -  In order to use the 
defined function (RegisterUserFunc) we need to register the 
function such that all the objects/methods descrivbed  in 
the functions are understood.

I may be wrong too...

1. Go to TOOLS -> Recovery scenario manager.
2. Select the trigger event that caused the error(it may be 
a pop up window).
3. Identify the name of the window with the help of 
POINTING HAND.
4. Choose the operation type : KEYBOARD OR MOUSE OPERATION.
5. Select the action with the help of POINTING HAND.(e.g. 
Click on OK button to close the window.)
6. If you want to add another action then keep "Add another 
recovery scenario" check box selected else de select it.
7. In the "Post recovery test run option" select "Proceed 
to next test iteration"
8. Give scenario name & description & click on finish 
button.
9. Save the scenario.
10. Go to TEST->SETTINGS->SCENARIO TAB....and add the saved 
scenario.
11. Click on APPLY & OK button......now your test run 
smoothly.

see... generally we can handle those pop up window exeptions
by writing If then statement and using exist method.

for example...

If window("skdhja").dialog("text:=fahda").exist then
window("skdhja").dialog("text:=fahda").winbutton("text:=OK(or)Cancel").click
window("akdhja").close
else
<write remaining script here..
end if
like this we can handle Pop Up window exceptions...try to
get control on script rather than QTP tool..

If any queries..
nanda.dreddy@gmail.com

If you select “Function call" option we have to select the 
file containing our library functions.
then we will have two radio buttons
1.Select function
2.Define new function
if we select the 'select function' radio button then we 
have to use the following syntax
Function (Object)
‘ recovery information and code goes here
End Function 

Example:
‘ Close the About Notepad window.
Function AboutWindow(Object)
Object.Highlight
Object.Close
End Function 


if we choose 'Define new function' then Create a new 
function by specifying a unique name for it, and defining 
the function in the Function Name box according to the 
displayed function prototype. The new function is added to 
the library file you selected.