Hi,
First check the data type of both objects are same or not.For merge dimension data type should be same.
Merging Dimensions & Rules at Business Objects Web Intelligence
A) Reports can be built where multiple source data can be synchronized.
B) Two or more similar dimensions of the same type can be merged. These different dimensions may come from different data sources or Report Queries.
C) Report Objects from different Queries can be included in the same Report Block by using the Merge Operation for synchronizing different Report Queries.
D) It is possible in Web Intelligence to merge large number of Queries.
E) N-number of dimension objects can be merged between 2 Queries provided the objects have the same data type.
F) While merging the dimension objects it should be kept in mind that if the 2 objects to be merged are of same type and value but the values are of different case (Lower Case & Upper Case) then the values will be treated as 2 distinct values.
G) If the values of 2 objects to be merged look exactly the same but if any one of them is having trailing blanks and the other one doesn’t then those values will be treated as 2 distinct values.
H) The most important point to be addressed is that only dimensions defined at the Universe can be merged we can not merge using variables.