[VB.net] Input Box - cancel button

[[venom]]

Hi there, I have a problem with INPUT BOX.

This is it:

dim variable1 as double

variable1 = CDbl(InputBox("What is your height?"))

Now, varible1 is double and whem I enter value into input box it is working.

Problem:
When I click cancel button, it sends empty string to this variable which leads to this error.

Conversion from string "" to type 'Double' is not valid.

Any help for me?