Layer mask does not move with Layer

no that is unfortunately not the problem. the image is just to illustrate that the link is indeed active. 🙂

it is just coincidence that i have the mask active in the screenshot.

but maybe i am a bit confused and this never worked this way:

i mean when i select a part of the image. i want to move a selected part of the image and the related part of the mask.

not the whole layer.

i am not using photoshop that much lately. i mean i can bring it on it´s own layer any move it.

but i thought it worked the way that when i select (and move) a part of an image that the relating part of the mask is linked (and moved) too. 

You only have the layer mask selected- it has the white box around it, that is your problem.

In the image below I have the image on 1 layer selected, not the layer mask. 

Click HOLD and drag as indicated in the image you should be good.