[TYPO3-mvc] findByProperty($property) return empty storage with string property

[Claus Fassing]

Hello,

I have a curious situation. The repository findByProperty method get 
back with null trying to fetch by a string (varchar) property. With an 
integer property I get my expected result and the curious thing is, on 
the local developer workstation everything is working. The developer 
workstation based on linux with Apache 2.2.x / php 5.3 / MySql 5.1.x and 
the live server based on linux with Apache 2.2.x / php 5.3 / MySql 5.1.x

Both are running TYPO3 4.5.6 (Extbase versions are identical)

I try to get the raw sql to investigate further in this direction, but 
it seems that extbase do not have any mechanism to get this, isn't it ?
Set debug on in Tx_Extbase_Persistence_Storage_Typo3DbBackend won't help 
in my situation cause I fetch my results through jQuery getJSON (typeNum 
variant)function an this debug code break the result with his content.

Is there anybody who run in a similar situation and can get me a hint 
how to investigate deeper ?

Regards Claus