Angular 无法从模块it was neither declared nor imported导出服务

I am trying to export an Service from one of my modules but i only get the following error:

ERROR Error: Uncaught (in promise): 
Error: Can't export value ConfirmDialogService from SharedModule as it was neither declared nor imported!

我的模块如下:

import { NgModule }                 from "@angular/core";
import { CommonModule }             from "@angular/common";
import { FormsModule }              from "@angular/forms";
import { RouterModule }             from "@angular/router";
import { MaterialModule }           from "@angular/material";

import { ConfirmDialogComponent }       from './confirm-dialog/confirm-dialog.component';
import { ConfirmDialogService }         from './confirm-dialog/confirm-dialog.service';

@NgModule({
    imports: [
        RouterModule,
        CommonModule,
        MaterialModule,
        FormsModule
    ],
    providers: [
        ConfirmDialogService
    ],
    declarations: [
        ConfirmDialogComponent 
    ],
    exports: [
        ConfirmDialogComponent 
        ConfirmDialogService
    ]
})
export class SharedModule {}

这些文件确实存在，并且在TS中被正确引用，但运行应用程序时会出现错误.