Using ifelse function for two matching strings/words

My question is simple. I've a dataset like this one:

     observed predicted probability result2
1     Head-up   Grazing   0.2727273   FALSE
2     Head-up   Grazing   0.7272727    TRUE
3     Head-up   Grazing   0.7272727    TRUE
4     Head-up   Grazing   0.5454545    TRUE
5     Head-up   Grazing   0.7272727    TRUE
6     Head-up   Grazing   0.4545455   FALSE
7     Head-up Vigilance   0.3636364   FALSE
8     Head-up   Grazing   0.3636364   FALSE
9     Head-up Vigilance   0.3636364   FALSE
10    Unknown   Grazing   0.3636364   FALSE
11     Moving   Head-up   0.4545455   FALSE
12     Moving   Head-up   0.3636364   FALSE

Where I've successfully created column results2 by using the ifelse function like so:

table$result1<-ifelse(table$probability>0.5,"TRUE","FALSE")

However, I'm trying to use the same function to create column result1, which would be:

table$result1<-ifelse(table$observed=table$predicted, "POSITIVE", "NEGATIVE")`. 

I'm getting the error Error: unexpected '=' in table$result1<-ifelse(table$observed=

Indeed, I'd like to have "POSITIVE" if the word on column observed matches the one on the column predicted of the same row, and "NEGATIVE" if vice versa..

Any ideas? Any help is appreciated!