Find the lowest leaf in a binary tree

i'm trying to compare all leafs to return the lowest value of a tree, I don't have main function just a script to insert values so unfortunately I can't debug it.

    tpNoArvore * findLowest(tpNoArvore * pNo){
       tpNoArvore * left;
       tpNoArvore * right;
       tpNoArvore * res;

       if (!pNo) return NULL; /* if */

       left = findLowest(pNo->pNoL);
       right = findLowest(pNo->pNoR);
       if(isLeaf(pNo))
          return pNo;
       }  /* if */

       if(!left){
          return right;
       } /* if */

       if(!right){
          return left;
       } /* if */


    return (left->Valor < right->Valor) ? left : right ;

} 

So, basically what i'm trying to achieve here is to compare the two sides of each node to find the lowest.