RTC 2009 R2 - Compilation of assembly - Pages

Hello everyone,

I have one problem with running a Page. I've read somewhere that could be a Bug in compiling from C/AL to C# but I am not sure.

p.s
I have Picture in attachment, but on German language. Translated to English means "Operator can not work with Types Double and Decimal"

this is a line of C# code in ....\Source\Page Folder. 50074.cs file
Rec.Target.SetFieldValueSafe(35, NavType.Decimal, new NavDecimal(ALCompiler.ToDecimal(tc.InvokePropertyGet<Double>(@GetPreis, 1))))

Does anyone know what could be the problem ?

1.) This is actualy one dll file with functions which we use with external application ( Automation ). I've tried to change Double into Decimal in Visual Studio, but doesn't help.
Now, I've tried just for testing purposes put Integer. With Integer everything it's OK, I can Compile Page and at the end I can run it.

But Integer is not appropriate, should be decimal or double :-k