Button not appearing on custom tab

Question

I'm attempting to add a tab to the Library contextual group. So far that works inside a Document Library. I can also see my Group on the new tab, but I don't see my button (will have more than one eventually). I also do see my tab if the Document Library is in a webpart.

Here is what I want to do in the end: The tab always shows in the Library contextual group. The Group is identical for all document types, but for specific document types it will show a specific button based on the document file extension (doc, docx, xls, xlsx, etc.). The only difference for the buttons, besides images, is that they'll execute certain commands. This is in order to leverage the Word Automation Services.

    <CommandUIDefinition Location="Ribbon.LibraryContextualGroup._children">      
      <Tab Id="Ribbon.WAS.Tab" 
        Title="Conversion"
        Description="Conversion Menu"
        Sequence="1001" >
        <Scaling Id="Ribbon.WAS.Tab.Scaling">
          <MaxSize Id="Ribbon.WAS.Group.MaxSize"
            GroupId="Ribbon.WAS.Groups.Group"
            Size="OneRow" />
        </Scaling>
        <Groups Id="Ribbon.WAS.Groups">
          <Group
            Id="Ribbon.WAS.Groups.Group"
            Sequence="1"
            Description="Converts documents"
            Template="Ribbon.WAS.GroupTemplate"
            Title="Document Conversion">
            <Controls Id="Ribbon.WAS.Controls">
              <Button Id="Ribbon.WAS.Controls.ToPdf"
                Sequence="1"
                LabelText="Contextual"
                Image16by16="/_layouts/Images/WAS/16x16Placeholder.png"
                Image32by32="/_layouts/Images/WAS/32x32Placeholder.png"
                TemplateAlias="o1"/>
            </Controls>
          </Group>
        </Groups>
      </Tab>
    </CommandUIDefinition>
  </CommandUIDefinitions>

Answer 1

Maybe the sequence number of the Group and Button tags isn't correct. SharePoint sequence numbers of default controls are based on multiples of 10. So to avoid collisions try changing the sequence number of the Group tag to 52 and the sequence number of the Button tag to 15 (For example).

EDIT:

You need to change the Size attribute in the MaxSize tag to the Title property value of the Layout tag.

For example if the Layout tag is like this:

<Layout 
  Title="OneLargeTwoMedium" 
  LayoutTitle="OneLargeTwoMedium"> 
  <Section Alignment="Top" Type="OneRow"> 
    <Row> 
      <ControlRef DisplayMode="Large" TemplateAlias="o1"  /> 
    </Row>
  </Section>
  <Section Alignment="Top" Type="TwoRow">
    <Row>
      <ControlRef DisplayMode="Medium" TemplateAlias="o2" />
    </Row>
    <Row>
      <ControlRef DisplayMode="Medium" TemplateAlias="o3" />
    </Row>
  </Section>
</Layout>

Change the Scaling tab from this:

<Scaling Id="Ribbon.WAS.Tab.Scaling">
 <MaxSize Id="Ribbon.WAS.Group.MaxSize"
   GroupId="Ribbon.WAS.Groups.Group"
   Size="OneRow" />
</Scaling>

To this:

<Scaling Id="Ribbon.WAS.Tab.Scaling">
 <MaxSize Id="Ribbon.WAS.Group.MaxSize"
   GroupId="Ribbon.WAS.Groups.Group"
   Size="OneLargeTwoMedium" />
</Scaling>

Complete Working Example:

<?xml version="1.0" encoding="utf-8"?>

<Elements xmlns="http://schemas.microsoft.com/sharepoint/">
  <CustomAction Id="Hello_world" RegistrationType="List" RegistrationId="101" Location="CommandUI.Ribbon" Sequence="5">
    <CommandUIExtension>
      <CommandUIDefinitions>
        <CommandUIDefinition Location="Ribbon.Templates._children">
          <GroupTemplate Id="Ribbon.WAS.GroupTemplate" >
            <Layout Title="bob" LayoutTitle="OneLargeTwoMedium">
              <Section Alignment="Top" Type="OneRow">
                <Row>
                  <ControlRef DisplayMode="Large" TemplateAlias="cust1" />
                </Row>
              </Section>
              <Section Alignment="Top" Type="TwoRow">
                <Row>
                  <ControlRef DisplayMode="Medium" TemplateAlias="cust2" />
                </Row>
                <Row>
                  <ControlRef DisplayMode="Medium" TemplateAlias="cust3" />
                </Row>
              </Section>
            </Layout>
          </GroupTemplate>
        </CommandUIDefinition>
        <CommandUIDefinition Location="Ribbon.LibraryContextualGroup._children">
          <Tab Id="Ribbon.WAS.Tab" Title="Conversion" Description="Conversion Menu" Sequence="501" >
            <Scaling Id="Ribbon.WAS.Tab.Scaling">
              <MaxSize Id="Ribbon.WAS.Group.MaxSize" GroupId="Ribbon.WAS.Groups.Group" Size="bob" />
            </Scaling>
            <Groups Id="Ribbon.WAS.Groups">
              <Group Id="Ribbon.WAS.Groups.Group" Sequence="52" Description="Converts documents" Template="Ribbon.WAS.GroupTemplate" Title="Document Conversion">
                <Controls Id="Ribbon.WAS.Controls">
                  <Button Id="Ribbon.WAS.Controls.ToPdf" Sequence="15" LabelText="Contextual" Command="Show_HelloWorld" Image16by16="/_layouts/images/placeholder32x32.png" Image32by32="/_layouts/images/placeholder32x32.png" TemplateAlias="cust1"/>
                </Controls>
              </Group>
            </Groups>
          </Tab>

        </CommandUIDefinition>
      </CommandUIDefinitions>

      <CommandUIHandlers>
        <CommandUIHandler Command="Show_HelloWorld" CommandAction="javascript:alert('Hello World!');" />
      </CommandUIHandlers>
    </CommandUIExtension>

  </CustomAction>
  </Elements>

Answer 2

I would make a separate button for each function, or make a polymorphic button that changes from a command called by the group command. (This is what determines if buttons should be on or off)

So make 1 button for each

Create a Group Command function that turns the groups on or off, and in this process you will be able or should be able to hide the buttons you don't want.

I think this should do it for you.