To provide some more details.
Small part of ribbon:
<customUI http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:im="iManage.WordVstoAddIn.15" xmlns:xxxxx="xxxxxxxx" xmlns="http://schemas.microsoft.com/office/2009/07/customui" loadImage="LoadImage" onLoad="RibbonLoad">
<commands>
<command idMso="FileNewDefault" onAction="FileNewOverride" />
<command idMso="PrintPreviewAndPrint" onAction="FilePrintOverride" />
</commands>
<ribbon startFromScratch="false">
<tabs>
<tab idQ="xxxxxxx" insertAfterMso="TabHome" label="RibbonForCustomVsto" keytip="X">
<group idQ="xxxxxxx" insertBeforeQ="xxxxxxxxx" label="Defaults" image="Icon_32_OtherTemplates">
<button id="XrefPanel" label="XRef" size="large" onAction="ShowXrefPanel" />
<box id="box0001" boxStyle="vertical">
<labelControl id="lbl001" label=" " />
<labelControl id="lbl002" label=" " />
<button id="btnRefreshAll" imageMso="RefreshAll" screentip="Refresh Document fields" getEnabled="ShowWizardGetEnabled" size="normal" onAction="UpdateDocumentCoiOnAction" />
</box>
<dialogBoxLauncher>
<button id="EditAuthors2" keytip="U" screentip="Edit your author list" onAction="EditAuthorsOnAction" />
</dialogBoxLauncher>
</group>
<group idQ="xxxxxxxxx" insertBeforeQ="xxxxxxxx" label="DMS" image="Icon_32_OtherTemplates">
<box id="boxDMSOpts1" boxStyle="vertical">
<control idMso="FileOpen" size="normal" />
<control idMso="FileClose" size="normal" />
<control idMso="FileSave" size="normal" />
</box>
<box id="boxDMSOpts12" boxStyle="vertical">
<editBox id="QuickOpen" tag="openDmsDocument" keytip="OO" screentip="xxxxx" getEnabled="RunCommandEnabled" onChange="RunCommandActionOnChange" />
<button id="EditProfile" tag="editDmsProfile" label="Edit Profile" keytip="OP" imageMso="FileProperties" screentip="Edit the document's DMS profile" getEnabled="RunCommandEnabled" size="normal" onAction="RunCommandAction" />
</box>
<splitButton id="BtnDocIdOptions" getVisible="InsertDocIdVisible" getEnabled="InsertDocIdEnabled" size="large">
<button id="BtnInsertDocId" label="Doc ID Options" image="Icon_64_AddDocRef" onAction="BtnInsertDocIdAction" />
<menu id="MnuInsertDocId">
<button id="BtnInsertDocId2" label="Doc ID Options" image="Icon_64_AddDocRef" onAction="BtnInsertDocIdAction" />
<button id="BtnRemoveDocId" label="Remove Doc ID" image="Icon_64_ReferenceRemoval" onAction="BtnRemoveDocIdAction" />
</menu>
</splitButton>
<control idMso="FileSaveAs" size="normal" />
</group>
</tab>
</tabs>
</ribbon>
</customUI>
LoadImage method:
public IPictureDisp LoadImage(string imageName)
I notice that - the LoadImage is not fired to load image for group, but if I set imageMso - is okey.
But I don't see any particular reason why event is not fired for custom icon.