Custom Ribbon for accde

[MichaelA]

I'm trying to create a custom ribbon for my accde file. I have some renaming to do but this is what I have so far. I works with the exception of this:

<group id="dbCustomGroup3" label="Open Forms"> <button id="btnOpen" label="Open Home Form"
onAction="=OpenMyForm('Navigation Form')"/>
</group>

When I try to open it, I get an error code "The expression you entered has a function name that Gradebook can't find"

What is wrong with it? The whole code is below.

<customUI xmlns="http://schemas.microsoft.com/office/2006/01/customui">
<ribbon startFromScratch="false">


<tabs>
<tab idMso="TabCreate" visible="false" />
<tab id="dbCustomTab" label="A Custom Tab" visible="true">
<group id="dbCustomGroup" label="Clipboard">
<control idMso="Paste" label="Built-in Paste" enabled="true"/>
</group>
<group id="dbCustomGroup2" label="External Data">
<control idMso="ImportExcel" label="Import from Excel" enabled="true"/>
<control idMso="ExportExcel" label="Export to Excel" enabled="true"/>
</group>
<group id="dbCustomGroup3" label="Open Forms">
<button id="btnOpen" label="Open Home Form"
onAction="=OpenMyForm('Navigation Form')"/>
</group>
</tab>
</tabs>
</ribbon>
</customUI>

Thank you!

[Micron]

Not an expert in ribbon xml but what I don't do is end a starting tag with a slash; e.g. <control idMso="Paste" label="Built-in Paste" enabled="true"> not
<control idMso="Paste" label="Built-in Paste" enabled="true"/>
Also have not tried to pass a parameter to a ribbon function as opposed to having the function call the appropriate procedure. Usually functions have parameters so that you can reuse them for every possible parameter value. If your called function only ever opens the same form, I'd get rid of the parameter.

Perhaps it is as simple as the function call isn't spelled the same way as the function itself. I'd also make sure the form isn't the culprit as I have no idea what Gradebook is.
EDIT - forgot to ask - if you're opening a main form for the application, why have a ribbon button for this as opposed to just loading the form on db opening?