a short (and most probably stupid) question

1. PVector center;
2.     PVector radius=new PVector(0, 0);
3.     float t;
4.    
5.     public void setup() {
6.       size(600, 600);
7.       smooth();
8.       center=new PVector(width/2, height/2);
9.      
10.     }
11.     public void draw() {
12.      
13.       background(50);
14.       noStroke();
15.       fill(255, 255, 0);
16.    
17.       if (mouseButton==LEFT) {
18.       t=0.1f;
19.       }if(mouseButton==RIGHT  ){
20.           t=-0.2f;
21.       }
22.      
    
23.       radius.x=constrain(lerp(radius.x, 400, t),0,400);
24.       radius.y=constrain(lerp(radius.y, 400, t),0,400);
25.      
26.       ellipse(center.x, center.y, radius.x,radius.y);
27.       println(t+" "+lerp(radius.x, 400, t));
28. }

why is this not working when i assign the same t value on both left & right click like this

1.   if (mouseButton==LEFT) {
2.       t=0.1f;
3.       }if(mouseButton==RIGHT  ){
4.           t=-0.1f;
5.       }

specifically, the right click does not work only if lerp(radius.x, 400, t) reaches its maximum value...
am i missing something?