Help me for identify and unpack .net programm

[tecnmarl]

Not everything can be loaded directly in a debugger.
Other than a "live" analysis there could be the need of a "cold" one.
The technical term is "static analysis".
Debuggers need to do some operations that could reveal them. For this reason, an anti reverse engineering technique is to detect a debugger and do some operations to obstruct them.
Sometimes we need to do some actions without executing the software.

In your specific case, the problem is not the packer, the problem is the exe. Check the sections and you will find something that is not right.