Visual Studio Team Services build cannot find .sln files

I am new to Visual Studio and Visual Studio Team Services.

I am trying to run a build on of simple code using Team Services. However, I get the following error:No solution was found using search pattern 'C:\a\1\s***.sln'.

My steps were:

1. In Team Services, create a team project, called Same New Project.
2. Open Visual Studio, configured my workspace.
3. In VS, created a new solution (Windows Form)
4. Checked in code.
5. In Team Services, selected Code from the menu and refreshed screen such that the new project.
6. Selected Build from menu.
7. Clicked on + sign to create a new build definition.
8. Selected Visual Studio. Clicked Next.
9. Checked Continuous integration (build whenever this branch is updated)
10. Selected Hosted under Default Agent Queue. Clicked Create.
11. See the image

12. Clicked Save.
13. Clicked Queue Build.
14. Clicked Ok.
15. After build completed, got posted error.
    Here is the console output:
    Hosted Agent successfully assigned.
    Configuring connection settings for Hosted Agent
    Starting Hosted Agent
    Initializing connection to Hosted Agent
    Successfully connected to Hosted Agent

    ---

Starting: Build

Executing the following commandline:

C:\LR\MMS\Services\Mms\TaskAgentProvisioner\Tools\agents\default\agent\worker\vsoWorker.exe /name:Worker-1c2934a8-bfde-429a-945e-4bb6394a6d3b /id:1c2934a8-bfde-429a-945e-4bb6394a6d3b /rootFolder:"C:\LR\MMS\Services\Mms\TaskAgentProvisioner\Tools\agents\default" /logger:Forwarding,1.0.0;Verbosity=Verbose,Name=Agent1-1aadeebb9c4390e852d65e80b5fec753;JobId=1c2934a8-bfde-429a-945e-4bb6394a6d3b

---

Starting: Get sources

Syncing repository: Sam New Project (TFVC)

Workspace Name: ws_1_1;Build\f1fca027-0a60-48e6-a5aa-f55071ee636c
Getting C:\a\1\s;C10
Getting C:\a\1\s\BuildProcessTemplates;C11
Getting C:\a\1\s\Sam New WIndows Form;C13
Getting C:\a\1\s\BuildProcessTemplates\AzureContinuousDeployment.11.xaml;C11
Getting C:\a\1\s\BuildProcessTemplates\DefaultTemplate.11.1.xaml;C11
Getting C:\a\1\s\BuildProcessTemplates\LabDefaultTemplate.11.xaml;C12
Getting C:\a\1\s\BuildProcessTemplates\UpgradeTemplate.xaml;C11
Getting C:\a\1\s\Sam New WIndows Form\Sam New WIndows Form;C13
Getting C:\a\1\s\Sam New WIndows Form\Sam New WIndows Form\App.config;C13
Getting C:\a\1\s\Sam New WIndows Form\Sam New WIndows Form\Form1.cs;C13
Getting C:\a\1\s\Sam New WIndows Form\Sam New WIndows Form\Form1.Designer.cs;C13
Getting C:\a\1\s\Sam New WIndows Form\Sam New WIndows Form\Program.cs;C13
Getting C:\a\1\s\Sam New WIndows Form\Sam New WIndows Form\Properties;C13
Getting C:\a\1\s\Sam New WIndows Form\Sam New WIndows Form\Sam New WIndows Form.csproj;C13
Getting C:\a\1\s\Sam New WIndows Form\Sam New WIndows Form\Sam New WIndows Form.csproj.vspscc;C13
Getting C:\a\1\s\Sam New WIndows Form\Sam New WIndows Form\Properties\AssemblyInfo.cs;C13
Getting C:\a\1\s\Sam New WIndows Form\Sam New WIndows Form\Properties\Resources.Designer.cs;C13
Getting C:\a\1\s\Sam New WIndows Form\Sam New WIndows Form\Properties\Resources.resx;C13
Getting C:\a\1\s\Sam New WIndows Form\Sam New WIndows Form\Properties\Settings.Designer.cs;C13
Getting C:\a\1\s\Sam New WIndows Form\Sam New WIndows Form\Properties\Settings.settings;C13
Done syncing repository Sam New Project to version C13 (workspace version C13)

---

Running tasks

Starting task: Build solution ***.sln

Executing the powershell script:

C:\LR\MMS\Services\Mms\TaskAgentProvisioner\Tools\agents\default\tasks\VSBuild\1.0.19\VSBuild.ps1
No solution was found using search pattern 'C:\a\1\s***.sln'.

---

Finishing task: VSBuild

Starting task: Copy Files to: $(build.artifactstagingdirectory)

Set workingFolder to default:

C:\LR\MMS\Services\Mms\TaskAgentProvisioner\Tools\agents\default\tasks\CopyFiles\1.0.10
found 0 files

---

Finishing task: CopyFiles

Starting task: Publish Artifact: drop

Set workingFolder to default:

C:\LR\MMS\Services\Mms\TaskAgentProvisioner\Tools\agents\default\tasks\PublishBuildArtifacts\1.0.25
Max Concurrent Uploads 2, Max Creators 1
Found 0 files to upload.
Created 0 files without uploading content. Total files processed 0
Uploaded artifact 'C:\a\1\a' to container folder 'drop' of build 7.
Associated artifact 6 with build 7

---

Finishing task: PublishBuildArtifacts

Task VSBuild failed. This caused the job to fail. Look at the logs for the task for more details.

Finishing Build

Worker Worker-1c2934a8-bfde-429a-945e-4bb6394a6d3b finished running job 1c2934a8-bfde-429a-945e-4bb6394a6d3b