I2C and SD Card

Now I have a question about I2C and simultaneous use of an SD card. I2C and SD function independently. Are both used in one code, the SD initialisation works no longer? I tested, to turn off the I2C interrupt, in the SD write time. Which unfortunately had absolutely no effect. Something important the SD Card is connectet to the Slave MCU.

TWCR &= (0<<TWIE);
LOG_DATA(&log_str[0], lls);
TWCR |= (1<<TWIE);

The transfer of the name of the file could be a problem to. The SD.Open routine does not return the correct name. But the file is created on the SD card???