I am having trouble with a blackjack game I am creating

I have buttons 1 - 13 (A-K)
I have 5 Textboxes which when the above buttons are pressed displays the values in the textboxes.

I also have one more textbox which adds up the values of the above 5 textboxes to give your Black Jack Total.


The problem I have is if an Ace (11) is in one of the textboxes and the Total Value exceeds 21 i need to have the Ace (11) change its value to 1 instead.

textbox 1 - 5 will be the card values
textbox6.text will be the total Value

I have tried......

Code:
if textbox6.text > 21 then and textbox1.text = 11 then textbox1.text = 1
This seems to work fine however it only solves the problem of an Ace (11) appearing in textbox1.text so i tried to repeat the code with the other boxes...

Code:
if textbox6.text > 21 then and textbox1.text = 11 then textbox1.text = 1
if textbox6.text > 21 then and textbox2.text = 11 then textbox2.text = 1
if textbox6.text > 21 then and textbox3.text = 11 then textbox3.text = 1
if textbox6.text > 21 then and textbox4.text = 11 then textbox4.text = 1
if textbox6.text > 21 then and textbox5.text = 11 then textbox5.text = 1
However this does not work and my program freezes?

Can anybody give me some code to resolve the problem. Not really bothered what the problem is just need a solution its driving me crazy