D-Link not functioning

Can I know, why my modem D-Link DWM-156 cannot detect the sim when i plugged in?
Can someone help me?

I know nothing about this 3G modem device, but a good place to start is by opening a terminal window and running

sudo tail -f /var/log/messages

then plug the device in. CTRTL-C to terminate.

Get the chipset details from

lsusb

and post the output here. Then someone may be able to advise further.

Here’s a recent thread concerning same (or similar) hardware

https://forums.opensuse.org/showthread.php/491570-Setup-D-link-DWM-156-3g-modem

*Depending on the chipset reported, it may be necessary to upgrade the usb_modeswitch-data package.