Problem with Update Context

Question

Hi All!

I'm trying to subtract the value of the field "Cantidad a comprar" to Available ("30 unidades disponibles) (you can see this in the attachment). This screen works with UpdateContext, this is a formula of a template (Assets).

I try to change "-1" with:

UpdateContext({NewRecord:Patch(Products,First(Filter(Products,ProductId=ItemSelected.ProductId)),{Available:Text(If(Value(ItemSelected.Available)>0,Value(ItemSelected.Available)-Value(Value5.text),ItemSelected.Available))})});Navigate(ConfirmationScreen,ScreenTransition.None)

But it doesn't work... and I don't understand why...

I hope you can help me!

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