Clearly, in this case your own macro didn't. Need anyone say more? Or are you going to blame the OP for having 'Option Explicit' set?
As for practical proof of macros that won't run correctly without declaring variables, see for example:
http://www.vbaexpress.com/forum/show...l=1#post414547
http://www.vbaexpress.com/forum/show...l=1#post363960
etc.
Delete the variable declarations there and the macros won't run...