Error #78 after solve with OptiStruct

Good evening to everybody,

I´m pretty new on working with Hypermesh and worked with videotutorials on youtube. 

Everytime I wanna use OptiStruct comes the same error #78. I don´t know what I´ve made wrong, so I put the files in the attachment and a screenshot of the error warning. 

I hope somebody can help me and i´m thankfull for every hint.

Greetings from Beginner93

<?xml version="1.0" encoding="UTF-8"?>

Unable to find an attachment - read this blog