i had to write this func. on an assignment

Code:
int checkMat(int**mat , int rows)
{
	int i,j;
	int sum=0;    // will be the sum of the first - the sum of the second if sum=0 then they're equal
	for (i=0;i<rows;i++)
		for(j=0;j<rows;j++)
			sum = sum+mat[i][j]-mat[rows-i][rows-j];
	if (sum=0) return 1;
	return 0;

}
now i want to test it in the main so i did :
Code:
	int arr[2][2]={{3,5},
					{9,4}};
        printf("%d",checkMat(arr[0],6));
and it gives a "argument of type incompatible" what am i doing wrong in the main ?

i don't want to change the signature of the function
tnx all helpers !