Try using coalesce in row 46 as shown below:
coalesce(${NQ1},0) + coalesce(${NQ2},0) + coalesce(${NQ3},0) + coalesce(${NQ4},0) + coalesce(${NQ5},0) + coalesce(${NQ6},0) + coalesce(${NQ7},0) + coalesce(${NQ8},0) + coalesce(${NQ9},0) + coalesce(${NQ10},0) + coalesce(${NQ11},0) + coalesce(${NQ12},0) + coalesce(${NQ13},0) + coalesce(${NQ14},0) + coalesce(${NQ15},0) + coalesce(${NQ16},0)
