mysql connect, while and close big problem

I make a connection A to get an array of result. Then use a while loop to use the array. In the while loop, I use the data to select other data by making a new connection. After printing the data, I close this new connection. After the while loop, I close the first connection too. If only have the first connection, it has no problem. But with the select in the while loop and close the new connection, it has an error on closing. Does anyone know why and how to fix it??