Reconfigure MachX02 using Wishbone

I'm trying to build a self-updater for the configuration of a MachXO2. 
It uses the EFB via Wishbone to reprogram the Configuration memory.

I'm able to successfully read the USERCODE using the interface as well 
as causing a REFRESH.

When I try to enter the configuration mode using the "74 08 00 00" 
command neither the fail bit nor the "configuration mode enabled" bit 
will be set. Also the busy bit is never set to one which it should 
considering the documentation says that you should wait 200us (or poll 
the busy bit).

I was not able to find any errors in my code after several days of 
debugging, so I think there must be some problem with the sysCONFIG I am 
using. Does the default configuration not allow reconfiguring the 
internal flash? And if so, what do I have to change?

Anyway, I have attached the code I am using. Sorry, comments are in 
German and there is some debug logic in it.

I really hope someone has successfully done this before and could geive 
me some advice.