"Activity used to start app doesn't exist or cannot be launched"

Hello guys,
I am new to appium and are currently trying to create a few simple tests to begin with. My issue is that I cannot launch the application under test at all, the only time it works is with the demo app included in the appium-dotnet-driver solution available via github https://github.com/appium/appium-dotnet-driver.

I have tried 2 different apps on my Nexus 5 and on several emulators but nothing will work (See attached message bellow). Is there som kind of standard on how to write capabilities and what should be included? I have been sitting with this for hours and tried all sorts of combinations but unfortunately I’m stuck here.

Thanks in advance / Jan

SetUp : System.InvalidOperationException : A new session could not be created. (Original error: Activity used to start app doesn’t exist or cannot be launched! Make sure it exists and is a launchable activity) (33)
at OpenQA.Selenium.Remote.RemoteWebDriver.UnpackAndThrowOnError(Response errorResponse)
at OpenQA.Selenium.Remote.RemoteWebDriver.Execute(String driverCommandToExecute, Dictionary`2 parameters)
at OpenQA.Selenium.Remote.RemoteWebDriver.StartSession(ICapabilities desiredCapabilities)
at OpenQA.Selenium.Remote.RemoteWebDriver…ctor(ICommandExecutor commandExecutor, ICapabilities desiredCapabilities)
at OpenQA.Selenium.Appium.AppiumDriver…ctor(ICommandExecutor commandExecutor, ICapabilities desiredCapabilities) in AppiumDriver.cs: line 81
at OpenQA.Selenium.Appium.AppiumDriver…ctor(Uri remoteAddress, ICapabilities desiredCapabilities, TimeSpan commandTimeout) in AppiumDriver.cs: line 114
at OpenQA.Selenium.Appium.Android.AndroidDriver…ctor(Uri remoteAddress, DesiredCapabilities desiredCapabilities, TimeSpan commandTimeout) in AndroidDriver.cs: line 54
at Appium.Samples.AppiumTest.BeforeAll() in AppiumTest.cs: line 38

As I said i have tried numerous combinations but here are a few I have been playing around with. Sometimes are all included sometimes just a few. And btw, the application is installed on my device, but it will not launch.

capabilities.SetCapability("appActivity", ".StartupActivity");
capabilities.SetCapability("appPackage", "com.company.androidapp");
capabilities.SetCapability("platformVersion", "4.3");
capabilities.SetCapability("platformName", "Android");
capabilities.SetCapability("appiumVersion", "1.3.4.1");
capabilities.SetCapability("app", "C:/Users/Jan.O/Downloads/app.apk");
capabilities.SetCapability("username", Env.getEnvVar("SAUCE_USERNAME"));
capabilities.SetCapability("accessKey", Env.getEnvVar("SAUCE_ACCESS_KEY"));
capabilities.SetCapability("name", "android - complex");
capabilities.SetCapability("tags", new string[] { "sample" });

Post your capabilities. This might help as well - https://github.com/appium/appium/blob/master/docs/en/writing-running-appium/running-tests.md

As I said i have tried numerous combinations but here are a few I have been playing around with. Sometimes are all included sometimes just a few. And btw, the application is installed on my device, but it will not launch.

    capabilities.SetCapability("appActivity", ".StartupActivity");
    capabilities.SetCapability("appPackage", "com.company.androidapp");
    capabilities.SetCapability("platformVersion", "4.3");
    capabilities.SetCapability("platformName", "Android");
    capabilities.SetCapability("appiumVersion", "1.3.4.1");
    capabilities.SetCapability("app", "C:/Users/Jan.O/Downloads/app.apk");
    capabilities.SetCapability("username", Env.getEnvVar("SAUCE_USERNAME"));
    capabilities.SetCapability("accessKey", Env.getEnvVar("SAUCE_ACCESS_KEY"));
    capabilities.SetCapability("name", "android - complex");
    capabilities.SetCapability("tags", new string[] { "sample" });

Case closed. My capabilities were overwritten and trying to launch incorrect activity.