there is a possibility your card may be not compatible. The test is simple. Format the card in Eclipse first – formatting is available under SETUP>UTILITY. Then try to save a preset to the card as #500. Use the knob to reach position 500 and check if the preset is there and can be loaded. If it's not there or can't be loadd, then the card is not compatible.
The manual has a list of compatible cards in the very last pages. There is also a list of other cards in one of our technotes on the Eventide website:
In general, you don't need a large capacity card, nor a very fast one.
Standard speed cards like the SanDisk SDCFB 256MB should work fine.