Problem with reading Sandisk 4gig hc micro sd card...

Question

I put the micro hc 4gig sd in the adapter, but my usb card reader does not recognise it, and also my toshiba laptop sd slot reader does not read it either, all my other normal sd cards work fine, and they are up to 2 gig sd cards, I purchased this 4gig micro,hc card for my mobile Phone, any help would be much appreciated