Peculiar Problem with Quartus 17.0 lite

Ok Let me explain in detail. Yes LTC2400 outputs 0-16777216 corresponding to 0-2.048V input ( 2.048 is used as Vref). I require only 1mV resolution for my application. So when I supply input of 1.25V, I get 10240000 counts. When right shifted by 10 bits and suffixing 2'b0, I get 10,000 counts which I display as 10.000 volts. This is the rationale for bits extraction. By the way this code runs like a horse in modelsim. But when synthesized and downloaded into the device, the execution goes crazy when subtracting 100.