ArgumentException: The input sequence was empty. when installing SpecFlow.NUnit

[agross]

Consider this packages.fsx:

source "http://nuget.org/api/v2"

nuget "SpecFlow.NUnit" "~> 1.1"

paket install yields:

Unhandled Exception: System.ArgumentException: The input sequence was empty.
Parameter name: source
   at Paket.Resolver.analyzeGraph@45(IDiscovery discovery, FSharpMap`2 processed, FSharpMap`2 dependencies) in D:\Users\agross\Downloads\Paket\src\Paket\Resolver.fs:line 67
   at Paket.LockFile.Update(String packageFile, String lockFile) in D:\Users\agross\Downloads\Paket\src\Paket\LockFile.fs:line 58
   at Paket.Process.Install(Boolean regenerate, Boolean force, String packageFile) in D:\Users\agross\Downloads\Paket\src\Paket\Process.fs:line 37
   at <StartupCode$Paket>.$Paket.Program.main@() in D:\Users\agross\Downloads\Paket\src\Paket\Program.fs:line 40

[forki]

No package found which matches NUnit 2.6

[forki]

Version available: ["2.5.10.11092"; "2.5.7.10213"; "2.5.9.10348"; "2.6.0.12051"; "2.6.0.12054"; "2.6.1"; 2.6.2"; "2.6.3"]

[forki]

this conflicts with the resolution of FSharp.Formatting. need to figure out the problem, but it should work for you