My question is: What is the relationship between malaria and schistosomiasis?

Therefor, I have plotted this GLMM;

sch1 <- asreml(fixed = sqrt(Schisto.elisa) ~ Malaria.RDT+Vil+Age+ wealth+water.score+Canoe+Bed.or.matress+ what.is.bilharzia+what.is.malaria+Trad.med, random=~FID+spl(Age), family = asreml.gaussian(link = "identity"), na.method.Y = "exclude", na.method.X = "exclude", data = dframe1)

From this model, I have tried to predict Malaria, however, when I use the predict function ASReml produces NA values.

The predict code is:

pred1 <- predict(sch1, classify = "Malaria.RDT:Vil:Age:wealth:water.score:Canoe:Bed.or.matress:what.is.bilharzia:what.is.malaria:Trad.med", levels =list(Malaria.RDT = seq(1,4), Vil=c("BUGOTO"), Age=mean(dframe1$Age), wealth=mean(dframe1$wealth), water.score=mean(dframe1$water.score), Canoe=c("0"), Bed.or.matress=("1"), what.is.bilharzia=c("1"), what.is.malaria=c("1"), Trad.med=("1")))

Obviously, I have validated my model e.t.c, and my supervisor has suggested that the problem is due to over specification of my model. I am not sure what this means, and Ideally just need to fix this problem.