problem while giving checkbox value to the registry

hi folks,

i have a problem while giving the checkbox value to the registry. i have got a dword value and at data i write a [mycheckboxvalue]. while the checkbox is checked there is no problem and a 1 enters the registry. but if the checkbox isn't checked a error pops up. in my opinion the value has to be zero if the checkbox isn't check but obviously it has no value. what is wrong?

greets Jonny