usb raw 2.0 timeout problem

[dudhar]

my program of usb read data..reading data from endpoint 2 of usb raw 2.0 is working properly when its in burst (timer mode) but when i am changing the configuration to burst(single short) mode its showing time out error.i have changed the time and tried but still getting error.and i also need information abt packet size and  packet transfer (maximum)so does any body is having idea abt that.please tell me.i am attaching that vi.

kind regards.
robin.