C2RU178 `Selectedmethod` (KEYMASKED/KEYENCRYPTED) data must be 16 hexadecimal characters

Explanation
You clicked OK on the KEYSMSTR key value or
PTKTDATA key value dialog but the length or the type of characters in the Key
value.. edit box is not 16 hexadecimal characters.

User response
Fix the value in the Key value.. edit box.