In the Landed Costs window, on the Costs tab, on the Fixed Costs subtab, you have chosen the New Landed Costs button.

In the Landed Costs - Setup window, you have a Cash Value Before Customs landed cost, and you have chosen the Update button, then the OK button.

On the Fixed Costs subtab, in the Amount column, you have entered an amount greater than zero.

You have attempted to select the Variable Costs subtab.

However, you have not split the fixed cost amount.

On the Fixed Costs subtab, enter an amount greater than zero.

Choose the Split button before you select the Variable Costs subtab.