3501i usb data cable problem pls pls HELP

[kukula]

i have 3510 usb data cable and 3510i mobile phone.

when i'm connecting the cable to the mobile and the usb to the computer it's all fine. the problem is that i can't turn on the mobile phone (it's not working).
when i take the usb off the computer and the cable is still connected to the mobile phone.. i can turn it on with no problem.

so my question is, whta is the problem ? i'm doing something wrong ?
do i need 3510i usb data cable instead of my 3510 data cable ?

there's differnt between 3510 serial cable and usb data cable ?


please please help i really don't know what to do.

Thanks