Custom Field Type behavior differs in Foundation and Enterprise Server

Hi Experts,

i wrote a Custom Field Type (SPFieldText) with no XSL for Rendering in Views and deployed to a Foundation-Platform.

Field Shows up in Edit,New and Display mode. Even in the AllItems-View the Field renders its value. 

Then i deployed same Field to a SharePoint-Server (Enterprise). The value does not Show up in Display-Form and AllItems-View but in Edit or New-Form.

After that surprising Situation i added an xsl-file with some coloring, just to see if the xsl renders the field value.

I deployed to both platforms. On Foundation everythings works fine!

On Enterprise Server still same result (Yes, i did iisreset and i also cleared the asp Cache).

I also added logging to this field and i can see, that on Enterprise-Server the Method GetfieldValue(string value) has null as ist value Parameter.

???

I can the the value in the Database of the Enterprise-Server and in EditForm.

Does anybody run into same issue?

Any Ideas how to solve this?

Thanks and Best Regards, Ronny