I am trying to do a tank foundation design. In Sliding check and lot of places where shears are reported I see values like -1.#10 kip. What am I doing wrong ?

The problem is that the Liquid height (Test) is entered as 0. Even if you do not want to add a test condition, you may just enter Test Fluid Weight as 0 but enter a Liquid Height (Test) as a nonzero value. You may enter Liquid height (Test) to be equal to the Liquid height ( Operating ). It would not matter as far as the calculations are concerned because the test fluid weight would be zero anyway. However if you enter Liquid Height ( Test ) as zero, it results in a division by zero situation, in which case, infinite values like (-1.#10 )show up in the calculation sheet.