OpenEMM Support

hi,
i use OpenEMM 2015 R2 on ubuntu 14.04 server 64bit.
i creted a template with several textblocks. In one of them i have follwing code
<h1>Mein toller text steht hier</h1>

When i try to create a new mailing i want to change the content of the h1-tag. when i click on the next-button i get an ...