I am troubleshooting an older instance of Sitecore where Form reports are blank for all WFFM forms. In my investigation, I found that the FormData collection is never created in MongoDB. I tested with a native install of 7.5 (rev. 141003) with the same version of WFFM (2.5 rev. 141014) and noticed that this collection was created during the WFFM installation (or at least it appeared to be created then).
I see the following errors corresponding to installation of the package:
ManagedPoolThread #9 11:29:29 ERROR Error executing command item: CampaignCommand Exception: System.Reflection.AmbiguousMatchException Message: Ambiguous match found. Source: mscorlib at System.DefaultBinder.SelectMethod(BindingFlags bindingAttr, MethodBase match, Type types, ParameterModifier modifiers) at System.RuntimeType.GetMethodImpl(String name, BindingFlags bindingAttr, Binder binder, CallingConventions callConv, Type types, ParameterModifier modifiers) at System.Type.GetMethod(String name, BindingFlags bindingAttr, Binder binder, Type types, ParameterModifier modifiers) at Sitecore.Tasks.CommandItem.Execute(Item items, ScheduleItem schedule)
19336 11:29:44 ERROR Error during aggregation. Exception: System.InvalidOperationException Message: Cannot use Analytics with a database that has no settings Source: Sitecore.Kernel at Sitecore.Diagnostics.Assert.ResultNotNull[T](T result, String message) at Sitecore.Analytics.Commons.LazyReference`1.GetValue(Object mutex, Func`1 initializer) at Sitecore.Analytics.Data.Items.AnalyticsItems.<get_PageEvents>b__6() at Sitecore.Analytics.Commons.LazyReference`1.GetValue(Object mutex, Func`1 initializer) at Sitecore.Analytics.Aggregation.Pipeline.FailuresProcessor.OnProcess(AggregationPipelineArgs args) at Sitecore.Analytics.Aggregation.Pipeline.AggregationProcessor.Process(AggregationPipelineArgs args) at (Object , Object ) at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args) at Sitecore.Analytics.Aggregation.InteractionAggregator.Aggregate(Byte recordKey, IAggregationContext context) at Sitecore.Analytics.Aggregation.Aggregator.Execute()
The second one appears to be most concerning. I have ran through all of the troubleshooting steps here: https://kb.sitecore.net/articles/977445. Though, I am still not seeing the FormData collection in MongoDB.