Hello User, How are you doing?Reg. your query Sony 1GB Memory Stick PRO DUO card on the URL http://www.mobymemory.com/proddetail.asp?prod=sony%5Fmspd1024%5F001 is perfectly compatible with your SE K750i.  All our card readers and memory cards are well tested for compatibility and reliabilty. We provide a lot of information through our site on "How to guides", Forums and also by emails, voice chat and chat support through our tech experts to our clients. We test and certify our memory cards for use with mobile phones so you don't have to MobyMemory memory cards carry a 5 yr manufacturer's warranty & 14-day money-back guarantee. What transfer device you are using USB cable or USB 2.0 card reader? Do you have our USB 2.0 MS Pro Duo compatible card reader. Always format the card on FAT using the card reader through your PC. Never format the card on phone. Is the card getting accessed through the card reader? Did you try accessing other compatible cards on your phone? Also check accessing other MS Pro cards on the reader? Is the LED on the reader blinking when you place the 1 GB sony card in the reader when you access it. The reader's LED should be continuously ON when you place any compatible card in the reader?  Do you get a message to format the card when you place it in the reader? Then go ahead as suggested. Also try accessing the card in another compatible device / phone? Also try repairing and checking the cards condition as suggested on the URL: http://www.mobymemory.com/Content/HOWTO.Repair.a.Corrupted.MobyMemory.Card.with.your.PC.24.html Try checking the condition of the card - http://www.mobymemory.com/Content/HOWTO.Check.the.condition.of.your.MobyMemory.MMC.47.html Still if you face any problems after these checks you can go for replacement by sending an email to returns@mobymemory.com with your Order ID, Complete name, Address and your case. We'll get back to you with a RMA (returns number) and other details. If you dont have a card reader, I also suggest you to go for buying a Card Reader as well for fastest transfer of music and video files to your mwemory cards, our standard recommendation will continue to be using a compatible USB2 card reader. This cuts the load time for a 2GB/1Gb/512MB memory card dramatically over Nokia DKU-2 or a bluetooth connection. Here is the URL: http://www.mobymemory.com/Memory_Card_readers.asp It is highly recommended to go for USB2 MS PRO DUO Memory Card Reader  http://www.mobymemory.com/proddetail.asp?prod=Reader%5FUSB2%5FMS%5FDUO Hope that helps..... Puneet 
Technical Support Team Moby Memory |