I have a Samsung Upstage SPH-M620. The original micro SD card for it was a Kingmax 64MB. I have recently bought one new SD card from SanDisk and it is 4GB. But it is not accepting it. Why is my Samsung Upstage SPH-M620 not accepting new 4GB memory card? Is it because of the SD card which is not from Kingmax or it is just my phone? Please help. I would really appreciate your useful information regarding this. Thanks.