AE linear() function is not working with variable

Question

I have set up a pretty simple expression that animates the number of copies of a shape layers' repeater:

copies = 14;
anim_start= 12;
anim_end = 32;

ftime = timeToFrames(time,25);
if(ftime<anim_end) 
x =linear(ftime,anim_start,anim_end,0,copies);
else 
x = linear(ftime,225,243,copies,0);
x;

It works fine if I replace "anim_end" with a number, but what it does now is have 0 copies at frame 11, and 14 copies one frame later. I am confused why AE won't exept my variable "anim_end". Can someone point me in the right direction?

thanks, Barbara

edit: since I can't comment on the answer that was already given: putting { brackets in the if-else clause did not change anything, unfortunately. Thanks anyway :)