resizing array[] erases its values to Vector3(0,0,0)

I coded a loop that looks for the tiles surrounding a tile that is clicked , and if one is found, the foundtiles array is resized,and a new tile position is added as the last value.

if I print the 4 tiles positions from the array within the loop, I get 4x positive Vector3 values, but if I print values from the array after the loop they are all 0, 0, 0 except the last one written which is positive, which means that the data in the array is being raised when I resize it.

here's the code:

         if (Physics.Raycast (ray, hit, 1000))
         {
             var objectposition = hit.collider.transform.position;
             for (var w1:int = 0; w1 < 4; w1 ++) {
                 for (var upwall in upwalls)
                     {
                         if (upwall.transform.position== petalvectors[w1]* sizemultiplier+objectposition)
                         {
                              z4=z4+1; 
                              foundwalls = new Vector3[z4];
                              foundwalls[z4-1] = petalvectors[w1]* sizemultiplier+objectposition;
 //print( foundwalls[z4-1]+ "zero"+foundwalls.length);prints 4x values                             
                         }
                     }
                 }
 print( foundwalls[1]+ "zero"+foundwalls.length);prints (0,0,0) except for foundwalls[3] the last written

if I am doing it wrong, how am I supposed to resize it?