diff --git a/src/config/floodscan.yml b/src/config/floodscan.yml
index 0831683..3cce4da 100644
--- a/src/config/floodscan.yml
+++ b/src/config/floodscan.yml
@@ -5,7 +5,7 @@ forecast: False
 extra_dims:
   - band : str
 test:
-  start_date: 1981-01-01
+  start_date: 1998-01-12
   end_date: Null
   iso3s: ["BDI", "NGA", "TCD"]
 coverage: ["DZA", "AGO", "BEN", "BWA", "BFA", "BDI", "CPV", "CMR", "CAF", "TCD", "COM", "COG", "CIV", "CAP", "DJI", "EGY", "GNQ", "ERI", "SWZ", "ETH", "GAB", "GMB", "GHA", "GIN", "GNB", "KEN", "LS0", "LBR", "LBY", "MDG", "MWI", "MLI", "MRT", "MUS", "MAR", "MOZ", "NAM", "NER", "NGA", "RWA", "STP", "SEN", "SYC", "SLE", "SOM", "ZAF", "SSD", "SDN", "TGO", "TUN", "UGA", "TZA", "ZMB", "ZWE"]
diff --git a/src/config/imerg.yml b/src/config/imerg.yml
index 35d28d3..02844a5 100644
--- a/src/config/imerg.yml
+++ b/src/config/imerg.yml
@@ -3,6 +3,6 @@ start_date: 2000-06-01
 end_date: Null
 forecast: False
 test:
-  start_date: 1981-01-01
+  start_date: 2000-06-01
   end_date: Null
   iso3s: ["BDI", "NGA", "TCD"]
diff --git a/src/utils/cog_utils.py b/src/utils/cog_utils.py
index 4f28c44..66a99a1 100644
--- a/src/utils/cog_utils.py
+++ b/src/utils/cog_utils.py
@@ -126,7 +126,7 @@ def process_floodscan(cog_name, mode):
     return da_in
 
 
-def stack_cogs(start_date, end_date, dataset="era5", mode="dev"):
+def stack_cogs(start_date, end_date, dataset, mode="dev"):
     """
     Stack Cloud Optimized GeoTIFFs (COGs) for a specified date range into an xarray Dataset.
 
@@ -173,11 +173,14 @@ def stack_cogs(start_date, end_date, dataset="era5", mode="dev"):
     cogs_list = [
         x.name
         for x in container_client.list_blobs(name_starts_with=prefix)
-        if (parse_date(x.name) >= start_date) & (parse_date(x.name) <= end_date)  # noqa
+        if (parse_date(x.name) >= start_date)
+        & (parse_date(x.name) <= end_date)  # noqa
     ]
 
     if len(cogs_list) == 0:
-        raise Exception("No COGs found to process")
+        raise Exception(
+            f"No COGs found to process: {start_date} to {end_date}"
+        )
 
     das = []