If you’re having trouble direct messaging you are likely not at a high enough “trust level”, i.e. trust level 0. By having limited functionality for brand new accounts it helps us cut down on bots that may spam the forums and/or users. Do a little reading and get your trust level up to 1 and you shouldn’t have a problem direct messaging. More on trust levels can be found here: What are Trust Levels and How do they Work?
Sorry about any inconvenience this may cause. It doesn’t take long getting to level 1.