please put this command in to your mikrotik ap:
/interface wireless print
And paste the output here.
We need some specific infor to help you.
Dont forget that some mikrotik wireless features are not compatible with other makes of hard ware. Nstreme is one and I have had problems with compression too.
Also you need to be sure your security settings are correct at both ends.
Have you tried the dlink 2100 in AP-Client mode?
I have more than 120 DWL-2100 acting as CPE to Mikrotik, so I know it works. We need to sort your settings out.