I keep getting constant output for my depth function of a tree

I keep getting the initialized value of max as my output for some reason

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
void maxi(struct TreeNode* A,int t,int k){
    if(A->left==NULL&&A->right==NULL&&t>k) k=t;
    if(A->left!=NULL) maxi(A->left,t+1,k);
    if(A->right!=NULL) maxi(A->right,t+1,k);
}

int Solution::maxDepth(TreeNode* A) {
    int l=0;
    maxi(A,1,l);
    return l;
}

The function keeps outputting initialized value of l. In this case 0.