How does a dependent child disqualify me from claiming qualifying widower?

[VolvoGirl]

When did your spouse die?  You can only claim qualifying widower for 2 years.  

You can file a Joint return the year your spouse died. For the next two years following a husband's or wife's death, the surviving spouse can file as a qualifying widow or widower if they have a qualifying child. That basically lets you continue to use the same tax brackets that apply to married-filing-jointly returns. After the year of death if you don't have a child you file as Single.