your problem is nothing to do with your devices but your Yoigo SIM....
perhaps your Yoigo SIM networks is not compatible with n900.....
remember n900 compatible networks is....

2G networks : GSM 850 / 900 / 1800 / 1900
3G networks : HSDPA 900 / 1700 / 2100

anything beyond that than it will not work on your n900....also 64k,128k & 256k SIM does have it differents....