Actually, Sukaldi, this is the SPSS forum.
I'm not very good with syntax, but the following will accomplish what you need:
COMPUTE NEW_VAR = DateVariableName + TimeVariableName.
EXECUTE.
Then go into the Variable View tab and select the new variable. Give it a new name, change the type to Date, and select dd-mmm-yyyy hh:mm format. (Yes, I'm sure there's a way to do that in syntax, but I'm not good enough to do that.)