Problem regarding setting up sender details: E-Mail verification doesn't work

hi! i have a problem regarding setting up my sender details - to be able to use the email marketing. you have to verify your domain and your personalized email-address. and i don't know why my email-address cannot be verified (it says: verification code is wrong - but it isn't...i found it in my inbox). The verification of my domain was successfully...what makes it even stranger to me.

any ideas?

thank you very much.