Your visa has to come from your port of origin which is from Pakistan, unless you hold the following passport, then visa are issue upon arrival.

Australia
Andorra
Austria
Brunei
Belgium
Denmark
Finland
France
Germany
Greece
Hong Kong
Iceland
Ireland
Italy
Japan
Liechtenstein
Luxembourg
Malaysia
Monaco
Netherlands
New Zealand
Norway Portugal
San Marino
Singapore
South Korea
Spain
Sweden
Switzerland
United Kingdom
United States of America
The Vatican