Schengen Visa stamp start date is after the requested start date

[yawasthi]

Hello,
I have a meeting in Belgium starting April 2 to April 6. I applied for the visa with my travel dates to Belgium as April 1-April 12 in application. Just received the visa and it is valid from April 3 to May 18. Since I have to enter Belgium on April 1 in order to make it to my meeting, what should I do? Did anyone have similar situation?
Thanks,

[cafeconleche]

Contact the consulate.