Error TS1086:An accessor cannot be declared in an ambient context

I have this problem and i can’t find the solution. Any thoughts?
Since I installed npm ionic2-calendar, start to have this problem. I’ve tried everything, reinstalling it, updating typescript, angular/cli, angular/core. I just don’t figure it out.

ERROR in node_modules/ionic2-calendar/calendar.d.ts(152,9): error TS1086: An accessor cannot be declared in an ambient context.

node_modules/ionic2-calendar/calendar.d.ts(153,9): error TS1086: An accessor cannot be declared in an ambient context.

node_modules/ionic2-calendar/calendar.service.d.ts(18,9): error TS1086: An accessor cannot be declared in an ambient context.

I just can’t start my app. Hope you guys can help me.