It sounds like you are trying to enter an amount on line 2008 "Total Tangible Capital Assets." This is a subtotal field. GIFI codes that are subtotal/total amounts are now non-edit due to CRA’s requirements to software developers. Subtotal/total codes should not be used to enter amounts. They must be calculated fields.
This means that TurboTax will automatically calculate the amount for this field by summing up all of your tangible capital assets (e.g. motor vehicles, buildings, equipment etc.), so you can "fill" this line in by entering amounts in these fields.
You can also just delete the line by right-clicking and selecting "Delete row."
