simple maths

i am trying to use the natural log in an equation that i'm using:

txtEs1.Text = txtEvap.Text * (Log ^ (0.4 * txtLAI.Text))

the normal Log doesn't work, how do i use natural log?

Thanks,
Liam

I don't know what exactly you are trying to calculate, but you cannot take just the Log or the Natural Log raised to some power. You need a number in parenthesis after the Log function or it will not work. This is from VB Help:

Log Function
Returns a Double specifying the natural logarithm of a number.
Syntax: Log(number)