format text(string) to double

hi, i'm new with VB and i'd like to know how to format a string into a double or an int.
Right now i'm using a grid control and I have matriceDialog.gridMatrice.Text of a certain row and column and I want to place it in an array of doubles.
MyArray(i,j) as double
when I do MyArray(i,j) = matriceDialog.gridMatrice.Text, it' says type mismatch(which I understand)

tank you

[Lothar Haensler]

MyArray(i,j) = CDbl(matriceDialog.gridMatrice.Text)

thanks a lot