Odata invalid filter and entityset problem

I have a problem with a odata service. If i test the odata with https option it works!

I can select and test with different URI options. Though when I click at the EntitySet button, I get the following error: I get status code 400 with error ' invalid filter. Provide filter for property x,x,x and x....'

So I type a filter behind the entityset but without success. This time the error is 'Invalid or no mapping to system data types found'

Do you know this message for https what does it mean? Can someone help here?

It is a simple odata service whith one entityset. The entitiset has got few fields. The 4 classes are generated and the dpc class is redefined (only the getentityset method). The logic is written and in the method the filter is written into code too. So what I forget to check?