Network Analyst - Tools have disappeared

Question

Hello community,

I work with the modelbuilder for the first time. After I've tested my model with the result "Calculation successful", I stored it. After one day, I wanted to continue my work. I saw, that all the the Input and output - Layer are still in it, but the tools have disappeared (can't clock it). I stored my file in serperate toolbox. 
So, what do i need to do, so that the model is correctly stored and still works after I open it again the next day?

Here is a small output of my model:

Thanks for your help,

king regards ,

Felix

Network Analyst Question.png

DanPatterson_Retired · Answer

Felix, I hate to throw you off to the tutorial, but it may be something in the way the model was setup, so have a look at the tutorial and compare your model setup with that in the guide.

Exercise 6: Creating a model for route analysis—Help | ArcGIS for Desktop

FelixBakker · Answer

I created one Model without parameters and one model with parameters. Both mdoels don't work because the tools have disappeared. I can't imagine why they dissapear, if I open the model the next day..

DanPatterson_Retired · Answer

I also noticed that your model has no parameters... it will just run with what you initially gave it... you are missing the

.... P ... Creating model parameters—Help | ArcGIS for Desktop