Web campaigns: 9 times out of 10? The embed code isn't installed correctly in the header. Double-check it!
B2C/B2B campaigns: Bad keyword selection. Single broad words like "Atlanta" won't work. Neither will misspelled or smashed-together phrases. Use the keyword research tools in AIpreneurs Business Lab. Find phrases people actually search.
B2C/B2B campaigns: Also check your Search Volume Estimator. If it shows low or zero volume for your keywords, you won't receive leads regardless of your budget. Aim for keywords with 200%+ of your daily target.