Look up the numeric location code before every call - DataForSEO locations are numbers (Germany is 2276), not ISO country codes. Use the /v3/appendix/locations helper endpoint to resolve the name to a code first. Hardcoding DE or US as the location is the classic mis-targeting bug: your SERP comes back for the wrong market and nothing errors loudly.

Context: DataForSEO field notes (seo-tools SKILL.md): location codes are NOT country codes - Germany is 2276, not DE. Passing a country code silently targets the wrong location or fails.