Terrain texture not covering all of terrain?

[H0rr0r Sc0pe]

I've added a terrain texture to my terrain but there are parts of the terrain that aren't being covered which are blue for some reason, my
texture doesn't contain any blue whatsoever it's made up of various shades of brown. How can I fix this?

My first instinct was to try painting a texture over it, however I can't seem to get this to work it always just raises ground as normal.
I followed a tutorial and did everything identical yet I'm not able to paint a texture on, I can only lower and raise the terrain with the paint
option selected.

I would prefer to know why the entire terrain hasn't been covered though and only resort to painting as a last option.

I appreciate any help

EDIT:Just for clarification when I see the terrain when designing it it appears to be fully covered, it's only when I test my game that it's missing texture in places.

[Chicken+Ribs Combo]

Don't use terrain, use landscape. How many textures are in your material including spec and normals? This can happen when there are too many textures in the terrain material.

[H0rr0r Sc0pe]

Just the one.

And I've already created my terrain now, I don't exactly have time to redo it.

[Solid Snake]

You can convert from Terrain to Landscape.

[H0rr0r Sc0pe]

I've got it sorted, when I was creating my heightmap because I was holding down ctrl I think I accidentally pressed another button and ended up duplicating the terrain
so I had to seperate sets. Thanks for the help anyway guys.

[Monkey-666]

I'd still consider converting it to Landscape. This page details how to do so down at the bottom.