If you are filing as Married Filing Jointly, BOTH spouses must have income (or be a full time student or disabled so they need assistance to take care of themselves) in order to qualify for the Dependent Care credit.
If the online version is allowing the credit, I suspect that you may have entered something differently. At any rate, if you are filing Jointly and are the only one with income, you do NOT qualify for the credit.
As a side note, for tax purposes you are NOT "Head of Household" if you live with your spouse. You are "Married Filing Jointly".
