使用个推时总是找不到pushmanager

在使用个推时,PushManager.getInstance().initialize(this.getApplicationContext());这个方法报错java.lang.NoClassDefFoundError: Failed resolution of: Lcom/igexin/sdk/PushManager;
Didn't find class "com.igexin.sdk.PushManager" on path: DexPathList[[zip file "/da