Why use a query with host variables and histogramms on the dependent table not BIND SENSITIVE?

Oracle 11.2.0.4 PSU1

Plattform AIX 6.1

A query with 3 joins and host variables don't use BIND SENSITIVE even if histogramms exists and a column FILLAG has only two different entries : one entry with 500 rows and another entry with 200.000 rows.

Do you know any reason why BIND SENSITIVE is not use? Too much where conditions? Too much host variables?

A join with 3 tables could not be the preventer because I can find a lot of statements with 3 joins and using BIND SENSITIVE (but with fewer "where" conditions)

Here the sql  which not will use BIND SENSITIVE:

select klpo.ukzlag ukzlag, klpo.fillag fillag, tes.tesnr tesnr, klpo.ukz ukz, klpo.aonr aonr, klpo.farbe farbe,