Force increment a for/next loop?

I’ve got some macro code like this:

For i = 1 to 200
x = Fx(something)

if isnull(x) then
	Next 
end if	

<some code>
Next

I’m testing to see if x is null. If it is, I want to go to the top of the For/Next loop and increment i and start again. But this code draws an error on the “end if”, saying it’s an orphan (no “if” statement).

So is this possible, or do I need a different kind of loop, or different routing?

Thanks.

Duh!:

For i = 1 to 200
x = Fx(something)

if isnull(x) then
    goto Nexti
end if  

<some code>
Nexti
Next